Emerging two-dimensional ternary transition metal dichalcogenide alloys have attracted much attention for their unique optical and optoelectronic properties,making them ideal candidates for optoelectronic applications...Emerging two-dimensional ternary transition metal dichalcogenide alloys have attracted much attention for their unique optical and optoelectronic properties,making them ideal candidates for optoelectronic applications.However,a comprehensive understanding of their quantum confinement effects and photoelectronic response characteristics remains crucial for device optimization and performance enhancement.In this study,we employed various spectroscopic techniques to investigate the optical properties and electronic band structures of molybdenum sulfide selenide(MoSSe)films with different layer numbers(4–11 layers).Our results revealed the splitting of Raman modes and shifting of phonon vibrational frequencies with increasing thickness,suggesting that MoSSe has strong interactions within the lattice.The A1g and E2g 1 modes were mainly shifted by internal strain and dielectric screening effect versus thickness,respectively.The redshift phenomenon of A and B excitons with increasing thickness was attributed to the leading effect of quantum confinement on exciton properties and optical band gaps.We observed a strong decrease in the direct bandgap spectral weight in photoluminescence(PL)when the layer number increased from 4 to 5.In addition,we have fabricated MoSSe photodetectors that exhibit a broadband response in the visible wavelength band of 350–800 nm.Furthermore,the observed enhancement in photocurrent and responsivity with increasing film thickness underscored the potential of MoSSebased devices for practical optoelectronic applications.This research contributes to advancing our fundamental understanding of MoSSe materials and paves the way for the design and development of high-performance optoelectronic devices.展开更多
Photoluminescence(PL) mechanism of carbon quantum dots(CQDs) remains controversial up to now even though a lot of approaches have been made. In order to do that, herein a PL color ladder from blue to near infrared of ...Photoluminescence(PL) mechanism of carbon quantum dots(CQDs) remains controversial up to now even though a lot of approaches have been made. In order to do that, herein a PL color ladder from blue to near infrared of CQDs with the absolute quantum yields higher than 70% were prepared via a one-pot hydrothermal synthesis route and separated by silica gel column.Time-correlated single photon counting measurements suggest that the electron transition takes in effect in the PL progress of the crystalline core-shell structured CQDs, and the PL properties could be coarsely adjusted by tuning the size of the crystalline carbon core owing to quantum confinement effects, and finely adjusted by changing the surface functional groups consisted shell owing to surface trap states,respectively. Both coarse and fine adjustments of PL, as optical and photoelectrical characterizations and density-functional theory(DFT) calculations have demonstrated, make it possible for top-level design and precise synthesis of new CQDs with specific optical properties.展开更多
Metal halide perovskites have generated significant attention in recent years because of their extraordinary physical properties and photovoltaic performance.Among these,inorganic perovskite quantum dots(QDs)stand out...Metal halide perovskites have generated significant attention in recent years because of their extraordinary physical properties and photovoltaic performance.Among these,inorganic perovskite quantum dots(QDs)stand out for their prominent merits,such as quantum confinement effects,high photoluminescence quantum yield,and defect-tolerant structures.Additionally,ligand engineering and an all-inorganic composition lead to a robust platform for ambient-stable QD devices.This review presents the state-of-the-art research progress on inorganic perovskite QDs,emphasizing their electronic applications.In detail,the physical properties of inorganic perovskite QDs will be introduced first,followed by a discussion of synthesis methods and growth control.Afterwards,the emerging applications of inorganic perovskite QDs in electronics,including transistors and memories,will be presented.Finally,this review will provide an outlook on potential strategies for advancing inorganic perovskite QD technologies.展开更多
We have measured the variation of photoluminescence(PL) in porous silicon with anodization(AO) time,HF soak time or natural oxidation time,and found that the peak value of PL spectrum will shift towards shorter value ...We have measured the variation of photoluminescence(PL) in porous silicon with anodization(AO) time,HF soak time or natural oxidation time,and found that the peak value of PL spectrum will shift towards shorter value as above time is increased.The analyses in experiment and theory show that the quantum confined structures produced by the AO process may be responsible for the blue shift.展开更多
This paper explores the band structure effect to elucidate the feasibility of an ultra-scaled GaAs Schottky MOSFET (SBFET) in a nanoscale regime. We have employed a 20-band sp3dSs* tight-binding (TB) approach to ...This paper explores the band structure effect to elucidate the feasibility of an ultra-scaled GaAs Schottky MOSFET (SBFET) in a nanoscale regime. We have employed a 20-band sp3dSs* tight-binding (TB) approach to compute E - K dis- persion. The considerable difference between the extracted effective masses from the TB approach and bulk values implies that quantum confinement affects the device performance. Beside high injection velocity, the ultra-scaled GaAs SBFET suffers from a low conduction band DOS in the F valley that results in serious degradation of the gate capacitance. Quan- tum confinement also results in an increment of the effective Schottky barrier height (SBH). Enhanced Schottky barriers form a double barrier potential well along the channel that leads to resonant tunneling and alters the normal operation of the SBFET. Major factors that may lead to resonant tunneling are investigated. Resonant tunneling occurs at low temperatures and low drain voltages, and gradually diminishes as the channel thickness and the gate length scale down. Accordingly, the GaAs (100) SBFET has poor ballistic performance in nanoscale regime.展开更多
The binding energies of excitons in quantum well structures subjected to an applied uniform electric field by taking into account the exciton longitudinal optical phonon interaction is calculated. The binding energies...The binding energies of excitons in quantum well structures subjected to an applied uniform electric field by taking into account the exciton longitudinal optical phonon interaction is calculated. The binding energies and corresponding Stark shifts for Ⅲ-Ⅴ and Ⅱ-Ⅵ compound semiconductor quantum well structures have been numerically computed. The results for GaAs/A1GaAs and ZnCdSe/ZnSe quantum wells are given and discussed. Theoretical results show that the exciton-phonon coupling reduces both the exciton binding energies and the Stark shifts by screening the Coulomb interaction. This effect is observable experimentally and cannot be neglected.展开更多
XB_(2)(X=Mg and Al)compounds have drawn great attention for their superior electronic characteristics and potential applications in semiconductors and superconductors.The study of phonon thermal transport properties o...XB_(2)(X=Mg and Al)compounds have drawn great attention for their superior electronic characteristics and potential applications in semiconductors and superconductors.The study of phonon thermal transport properties of XB_(2)is significant to their application and mechanism behind research.In this work,the phonon thermal transport properties of three-dimensional(3D)and two-dimensional(2D)XB_(2)were studied by first-principles calculations.After considering the electron-phonon interaction(EPI),the thermal conductivities(TCs)of 3D Mg B_(2)and 3D Al B_(2)decrease by 29%and 16%which is consistent with experimental values.Moreover,the underlying mechanisms of reduction on lattice TCs are the decrease in phonon lifetime and heat capacity when considering quantum confinement effect.More importantly,we are surprised to find that there is a correlation between quantum confinement effect and EPI.The quantum confinement will change the phonon and electron characteristics which has an impact on EPI.Overall,our work is expected to provide insights into the phonon thermal transport properties of XB_(2)compounds considering EPI and quantum confinement effect.展开更多
Layered two dimensional(2D) or quasi-2D perovskites are emerging photovoltaic materials due to their superior environment and structure stability in comparison with their 3D counterparts. The typical 2D perovskites ca...Layered two dimensional(2D) or quasi-2D perovskites are emerging photovoltaic materials due to their superior environment and structure stability in comparison with their 3D counterparts. The typical 2D perovskites can be obtained by cutting 3D perovskites along < 100 > orientation by incorporation of bulky organic spacers, which play a key role in the performance of 2D perovskite solar cells(PSCs). Compared with aliphatic spacers, aromatic spacers with high dielectric constant have the potential to decrease the dielectric and quantum confinement effect of 2D perovskites, promote efficient charge transport and reduce the exciton binding energy, all of which are beneficial for the photovoltaic performance of 2D PSCs. In this review, we aim to provide useful guidelines for the design of aromatic spacers for 2D perovskites. We systematically reviewed the recent progress of aromatic spacers used in 2D PSCs. Finally, we propose the possible design strategies for aromatic spacers that may lead to more efficient and stable 2D PSCs.展开更多
DG-MOSFETs are the most widely explored device architectures for na</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="f...DG-MOSFETs are the most widely explored device architectures for na</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">no-scale CMOS circuit design in sub-50 nm due to the improved subthre</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">shold slope and the reduced leakage power compared to bulk MOSFETs. In thin-film (</span><i><span style="font-family:Verdana;">t</span><sub><span style="font-family:Verdana;">si</span></sub></i><span style="font-family:Verdana;"> < 10 nm) DG-MOS structures, charge carriers are affected</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> by</span></span></span><span><span><span style="font-family:""> <i><span style="font-family:Verdana;">t</span><sub><span style="font-family:Verdana;">si</span></sub></i><span style="font-family:Verdana;">-</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">induced quantum confinement along with the confinement caused by </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">very high electric field at the interface. Therefore, quantum confinement effects on the device characteristics are also quite important and it needs to be incorpo</span><span style="font-family:Verdana;">rated along with short channel effects for nano-scale circuit design. In this</span> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">paper</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">, we analyze</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">d</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> a DG-MOSFET structure at </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">20 nm technology node</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> incorporating quantum confinement effects and various short channel effects. The effect of physical parameter variations on performance characteristics of </span><span><span style="font-family:Verdana;">the device such as threshold voltage, subthreshold slope, </span><i><span style="font-family:Verdana;">I</span><sub><span style="font-family:Verdana;">ON</span></sub></i><span style="font-family:Verdana;"> - </span><i><span style="font-family:Verdana;">I</span><sub><span style="font-family:Verdana;">OFF</span></sub></i><span style="font-family:Verdana;"> ratio,</span></span> <i><span style="font-family:Verdana;">DIBL</span></i></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> etc. has been investigated and plotted through extensive TCAD simulations. The physical parameters considered in this </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">paper</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> are operating temperature </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">T</span><sub><span style="font-family:Verdana;">op</span></sub></i><span style="font-family:Verdana;">), channel doping concentration (</span><i><span style="font-family:Verdana;">N</span><sub><span style="font-family:Verdana;">c</span></sub></i><span style="font-family:Verdana;">), gate oxide thickness (</span><i><span style="font-family:Verdana;">t</span><sub><span style="font-family:Verdana;">ox</span></sub></i><span style="font-family:Verdana;">) an</span></span><span style="font-family:Verdana;">d Silicon film thickness (</span><i><span style="font-family:Verdana;">t</span><sub><span style="font-family:Verdana;">si</span></sub></i><span style="font-family:Verdana;">). It </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">was</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> observed that quantum confinement of </span><span style="font-family:Verdana;">charge </span><span style="font-family:Verdana;">carriers significantly affect</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">ed</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the performance characteristics (mostly the</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> subth</span><span style="font-family:Verdana;">reshold characteristics) of the device and therefore, it cannot be ignored in</span><span style="font-family:Verdana;"> the </span><span style="font-family:Verdana;">subthreshold region</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">based circuit design like in many previous research</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> works. </span><span><span style="font-family:Verdana;">The ATLAS</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> device simulator has been used in this </span></span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">paper</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> to perform simu</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">lation and parameter extraction. The TCAD analysis presented in the</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> manuscript can be incorporated for device modeling and device</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> matching. It can be used to illustrate exact device behavior and for proper device control.展开更多
A compact model for the integrated inversion charge density Qi in double-gate (DG-) MOSFETs is developed. For nanoscale applications,quantum confinement of the inversion carriers must be taken into account. Based on...A compact model for the integrated inversion charge density Qi in double-gate (DG-) MOSFETs is developed. For nanoscale applications,quantum confinement of the inversion carriers must be taken into account. Based on the previous work of Ge, we establish an expression for the surface potential with respect to Qi, and form an implicit equation, from which Qi can be solved. Results predicted by our model are compared to published data as well as results from Schred,a popular 1D numerical solver that solves the Poisson's and Schr6dinger equa- tions self-consistently. Good agreement is obtained for a wide range of silicon layer thickness,confirming the supe- riority of this model over previous work in this field.展开更多
Quantum confinement effect(QCE), an essential physical phenomenon of semiconductors when the size becomes comparable to the exciton Bohr radius, typically results in quite different physical properties of low-dimens...Quantum confinement effect(QCE), an essential physical phenomenon of semiconductors when the size becomes comparable to the exciton Bohr radius, typically results in quite different physical properties of low-dimensional materials from their bulk counterparts and can be exploited to enhance the device performance in various optoelectronic applications. Here, taking Cs Pb Br3 as an example, we reported QCE in all-inorganic halide perovskite in two-dimensional(2D) nanoplates. Blue shifts in optical absorption and photoluminescence spectra were found to be stronger in thinner nanoplates than that in thicker nanoplates, whose thickness lowered below -7 nm. The exciton binding energy results showed similar trend as that obtained for the optical absorption and photoluminescence. Meanwile, the function of integrated intensity and full width at half maximum and temperature also showed similar results, further supporting our conclusions. The results displayed the QCE in all-inorganic halide perovskite nanoplates and helped to design the all-inorganic halide perovskites with desired optical properties.展开更多
Silicon nanoparticles have attracted great attention in the past decades because of their intriguing physical properties, active surface state, distinctive photoluminescence and biocompatibility. In this review, we pr...Silicon nanoparticles have attracted great attention in the past decades because of their intriguing physical properties, active surface state, distinctive photoluminescence and biocompatibility. In this review, we present some of the recent progress in preparation methodologies and surface functionalization approaches of silicon nanoparticles. Further, their promising applications in the fields of energy and electronic engineering are introduced.展开更多
The binding energy and effective mass of a polaron confined in a GaAs film deposited on an AlGal-xAs substrate are investigated, for different film thickness values and aluminum concentra- tions and within the framewo...The binding energy and effective mass of a polaron confined in a GaAs film deposited on an AlGal-xAs substrate are investigated, for different film thickness values and aluminum concentra- tions and within the framework of the fractional-dimensional space approach. Using this scheme, we propose a new method to define the effective length of the quantum confinement. The limita- tions of the definition of the original effective well width are discussed, and the binding energy and effective mass of a polaron confined in a GaAs film are obtained. The fl-actional-dimensional theo- retical results are shown to be in good agreement with previous, more detailed calculations based on second-order perturbation theory.展开更多
Nanocrystalline (nc) 3C-SiC films on the Si substrate were prepared by the helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) technique. With the SiH4-CH4 gas flow ratio changing, the films exhibit ...Nanocrystalline (nc) 3C-SiC films on the Si substrate were prepared by the helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) technique. With the SiH4-CH4 gas flow ratio changing, the films exhibit different photoluminescence (PL) characteristics. Under the stoichiometric condition, the PL peak redshift from 470 nm to 515 nm is detected with the increase of excitation wavelength, which can be attributed to the quantum confinement effect radiation of 3C-SiC nanocrystals of different sizes. However, the appearance of an additional PL band at 436 nm in Si-rich film might be sourced back to the excess of Si defect centers in it. This is also the case for C-rich film for its PL band lying at 570 nm. The results above quoted indicate an important influence of gas flow ratio on the PL properties of the SiC films providing an effective guidance for analyzing the luminescence mechanism and exploring the high-efficiency light emission of the SiC films.展开更多
In nanomaterials, optical anisotropies reveal a fundamental relationship between structural and optical properties, in which directional optical properties can be exploited to enhance the performance of optoelectronic...In nanomaterials, optical anisotropies reveal a fundamental relationship between structural and optical properties, in which directional optical properties can be exploited to enhance the performance of optoelectronic devices. First principles calculation based on density functional theory (DFT) with the generalized gradient approximation (GGA) are carried out to investigate the energy band gap structure on silicon (Si) and germanium (Ge) nanofilms. Simulation results show that the band gaps in Si (100) and Ge (111) nanofilms become the direct-gap structure in the thickness range less than 7.64 nm and 7.25 nm respectively, but the band gaps of Si (111) and Ge (110) nanofilms still keep in an indirect-gap structure and are independent on film thickness, and the band gaps of Si (110) and Ge (100) nanofilms could be transferred into the direct-gap structure in nanofilms with smaller thickness. It is amazing that the band gaps of Si(1-x)/ZGexSi(1-x)/2 sandwich structure become the direct-gap structure in a certain area whether (111) or (100) surface. The band structure change of Si and Ge thin films in three orientations is not the same and the physical mechanism is very interesting, where the changes of the band gaps on the Si and Ge nanofilms follow the quantum confinement effects.展开更多
Isolated graphene nanoribbons(GNRs)usually have energy gaps,which scale with their widths,owing to the lateral quantum confinement effect of GNRs.The absence of metallic GNRs limits their applications in device interc...Isolated graphene nanoribbons(GNRs)usually have energy gaps,which scale with their widths,owing to the lateral quantum confinement effect of GNRs.The absence of metallic GNRs limits their applications in device interconnects or being one-dimensional physics platform to research amazing properties based on metallicity.A recent study published in Science provided a novel method to produce metallic GNRs by inserting a symmetric superlattice into other semiconductive GNRs.This finding will broader the applications of GNRs both in nanoelectronics and fundamental science.展开更多
The quantum confinement effect is important in nanoelectronics and optoelectronics applications; however, there is a discrepancy between the theory of quantum confinement, which indicates that band-gap widening occurs...The quantum confinement effect is important in nanoelectronics and optoelectronics applications; however, there is a discrepancy between the theory of quantum confinement, which indicates that band-gap widening occurs only at small sizes, and experimental observations of band-gap widening in large-diameter nanowires (NWs). This paper reports an obvious blue shift of the absorption edge in the UV-visible absorption spectra of SiC NWs with diameters of 50-300 nm. On the basis of quantum confinement theory and high-resolution transmission electron microscopy images of SiC NWs, band-gap widening in SiC NWs with diameters of up to hundreds of nanometers is fully explained; the results could help to explain similar band-gap widening in other NWs with large diameters.展开更多
The growth of nanocrystalline PbS films by chemical bath deposition (CBD) onto glass at temperatureT = 40 ± 2℃, is presented in this research. We report on the modification of structural, optical nanostructure...The growth of nanocrystalline PbS films by chemical bath deposition (CBD) onto glass at temperatureT = 40 ± 2℃, is presented in this research. We report on the modification of structural, optical nanostructures due to in situ Hg-doping.The morphological changes of the layers were analyzed using AFM. XRD spectra displayed peaks at 20 = (26.00, 30.07, 43.10, 51.00, 53.48), indicating growth on the zinc blende face. The grain size determined by x-rays diffraction of the undoped samples, was found -36 nm, whereas with the doped sample was 32-23 nm. Optical absorption, transition direct and indirect the forbidden band gap energy (Eg) shifts discloses a shift in the range 1.45-2.4 eV.展开更多
The energy level separation between the edge states in topological insulator quantum dots lies in the terahertz(THz) range.Quantum confinement ensures the nonuniformity of the energy level separation near the Dirac po...The energy level separation between the edge states in topological insulator quantum dots lies in the terahertz(THz) range.Quantum confinement ensures the nonuniformity of the energy level separation near the Dirac point. Based on these features, we propose that a topological insulator quantum dot array can be operated as an electrically pumped continuous-wave THz laser. The proposed device can operate at room temperature, with power exceeding 10 mW and quantum efficiency reaching ~50%. This study may promote the usage of topological insulator quantum dots as an important source of THz radiation.展开更多
InGaN quantum dots (QDs) have attracted many research interests in recent years for their potentials to realize long wavelength visible emission from green to red, which can pave a way to fabricate the phosphor-free...InGaN quantum dots (QDs) have attracted many research interests in recent years for their potentials to realize long wavelength visible emission from green to red, which can pave a way to fabricate the phosphor-free white light emitting diodes (LEDs). In this paper, we reported our recent progresses on InGaN QD LEDs, the discussions were dedicated to the basic physics model of the strain relaxation in self-assembled InGaN QDs, the growth of InGaN QDs with a growth interruption method by metal organic vapor phase epitaxy, the optimization of GaN barrier growth in multilayer InGaN QDs, the demonstration of green, yellow-green and red InGaN QD LEDs, and future challenges.展开更多
基金financially supported by the National Natural Science Foundation of China(U2230108,62275053)the National Key R&D Program of China(2021YFB2012601).
文摘Emerging two-dimensional ternary transition metal dichalcogenide alloys have attracted much attention for their unique optical and optoelectronic properties,making them ideal candidates for optoelectronic applications.However,a comprehensive understanding of their quantum confinement effects and photoelectronic response characteristics remains crucial for device optimization and performance enhancement.In this study,we employed various spectroscopic techniques to investigate the optical properties and electronic band structures of molybdenum sulfide selenide(MoSSe)films with different layer numbers(4–11 layers).Our results revealed the splitting of Raman modes and shifting of phonon vibrational frequencies with increasing thickness,suggesting that MoSSe has strong interactions within the lattice.The A1g and E2g 1 modes were mainly shifted by internal strain and dielectric screening effect versus thickness,respectively.The redshift phenomenon of A and B excitons with increasing thickness was attributed to the leading effect of quantum confinement on exciton properties and optical band gaps.We observed a strong decrease in the direct bandgap spectral weight in photoluminescence(PL)when the layer number increased from 4 to 5.In addition,we have fabricated MoSSe photodetectors that exhibit a broadband response in the visible wavelength band of 350–800 nm.Furthermore,the observed enhancement in photocurrent and responsivity with increasing film thickness underscored the potential of MoSSebased devices for practical optoelectronic applications.This research contributes to advancing our fundamental understanding of MoSSe materials and paves the way for the design and development of high-performance optoelectronic devices.
基金supported by the National Natural Science Foundation of China(21535006)
文摘Photoluminescence(PL) mechanism of carbon quantum dots(CQDs) remains controversial up to now even though a lot of approaches have been made. In order to do that, herein a PL color ladder from blue to near infrared of CQDs with the absolute quantum yields higher than 70% were prepared via a one-pot hydrothermal synthesis route and separated by silica gel column.Time-correlated single photon counting measurements suggest that the electron transition takes in effect in the PL progress of the crystalline core-shell structured CQDs, and the PL properties could be coarsely adjusted by tuning the size of the crystalline carbon core owing to quantum confinement effects, and finely adjusted by changing the surface functional groups consisted shell owing to surface trap states,respectively. Both coarse and fine adjustments of PL, as optical and photoelectrical characterizations and density-functional theory(DFT) calculations have demonstrated, make it possible for top-level design and precise synthesis of new CQDs with specific optical properties.
基金The authors thank the support from the Australian Research Council(DP190103316)UNSW SHARP Project(RG163043).
文摘Metal halide perovskites have generated significant attention in recent years because of their extraordinary physical properties and photovoltaic performance.Among these,inorganic perovskite quantum dots(QDs)stand out for their prominent merits,such as quantum confinement effects,high photoluminescence quantum yield,and defect-tolerant structures.Additionally,ligand engineering and an all-inorganic composition lead to a robust platform for ambient-stable QD devices.This review presents the state-of-the-art research progress on inorganic perovskite QDs,emphasizing their electronic applications.In detail,the physical properties of inorganic perovskite QDs will be introduced first,followed by a discussion of synthesis methods and growth control.Afterwards,the emerging applications of inorganic perovskite QDs in electronics,including transistors and memories,will be presented.Finally,this review will provide an outlook on potential strategies for advancing inorganic perovskite QD technologies.
文摘We have measured the variation of photoluminescence(PL) in porous silicon with anodization(AO) time,HF soak time or natural oxidation time,and found that the peak value of PL spectrum will shift towards shorter value as above time is increased.The analyses in experiment and theory show that the quantum confined structures produced by the AO process may be responsible for the blue shift.
文摘This paper explores the band structure effect to elucidate the feasibility of an ultra-scaled GaAs Schottky MOSFET (SBFET) in a nanoscale regime. We have employed a 20-band sp3dSs* tight-binding (TB) approach to compute E - K dis- persion. The considerable difference between the extracted effective masses from the TB approach and bulk values implies that quantum confinement affects the device performance. Beside high injection velocity, the ultra-scaled GaAs SBFET suffers from a low conduction band DOS in the F valley that results in serious degradation of the gate capacitance. Quan- tum confinement also results in an increment of the effective Schottky barrier height (SBH). Enhanced Schottky barriers form a double barrier potential well along the channel that leads to resonant tunneling and alters the normal operation of the SBFET. Major factors that may lead to resonant tunneling are investigated. Resonant tunneling occurs at low temperatures and low drain voltages, and gradually diminishes as the channel thickness and the gate length scale down. Accordingly, the GaAs (100) SBFET has poor ballistic performance in nanoscale regime.
基金Project supported in part by the National Natural Science Foundation of China (Grant No 10164003) and the Natural Science Foundation of Inner Mongol of China (Grant No 200408020101).
文摘The binding energies of excitons in quantum well structures subjected to an applied uniform electric field by taking into account the exciton longitudinal optical phonon interaction is calculated. The binding energies and corresponding Stark shifts for Ⅲ-Ⅴ and Ⅱ-Ⅵ compound semiconductor quantum well structures have been numerically computed. The results for GaAs/A1GaAs and ZnCdSe/ZnSe quantum wells are given and discussed. Theoretical results show that the exciton-phonon coupling reduces both the exciton binding energies and the Stark shifts by screening the Coulomb interaction. This effect is observable experimentally and cannot be neglected.
基金financially supported by the National Natural Science Foundation of China(Nos.51720105007,52076031 and 51806031)the Fundamental Research Funds for the Central Universities(No.DUT19RC(3)006)the computing resources from Super-computing Center of Dalian University of Technology。
文摘XB_(2)(X=Mg and Al)compounds have drawn great attention for their superior electronic characteristics and potential applications in semiconductors and superconductors.The study of phonon thermal transport properties of XB_(2)is significant to their application and mechanism behind research.In this work,the phonon thermal transport properties of three-dimensional(3D)and two-dimensional(2D)XB_(2)were studied by first-principles calculations.After considering the electron-phonon interaction(EPI),the thermal conductivities(TCs)of 3D Mg B_(2)and 3D Al B_(2)decrease by 29%and 16%which is consistent with experimental values.Moreover,the underlying mechanisms of reduction on lattice TCs are the decrease in phonon lifetime and heat capacity when considering quantum confinement effect.More importantly,we are surprised to find that there is a correlation between quantum confinement effect and EPI.The quantum confinement will change the phonon and electron characteristics which has an impact on EPI.Overall,our work is expected to provide insights into the phonon thermal transport properties of XB_(2)compounds considering EPI and quantum confinement effect.
基金financially supported by National Natural Science Foundation of China (Grants Nos. 52273182, 21875122)。
文摘Layered two dimensional(2D) or quasi-2D perovskites are emerging photovoltaic materials due to their superior environment and structure stability in comparison with their 3D counterparts. The typical 2D perovskites can be obtained by cutting 3D perovskites along < 100 > orientation by incorporation of bulky organic spacers, which play a key role in the performance of 2D perovskite solar cells(PSCs). Compared with aliphatic spacers, aromatic spacers with high dielectric constant have the potential to decrease the dielectric and quantum confinement effect of 2D perovskites, promote efficient charge transport and reduce the exciton binding energy, all of which are beneficial for the photovoltaic performance of 2D PSCs. In this review, we aim to provide useful guidelines for the design of aromatic spacers for 2D perovskites. We systematically reviewed the recent progress of aromatic spacers used in 2D PSCs. Finally, we propose the possible design strategies for aromatic spacers that may lead to more efficient and stable 2D PSCs.
文摘DG-MOSFETs are the most widely explored device architectures for na</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">no-scale CMOS circuit design in sub-50 nm due to the improved subthre</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">shold slope and the reduced leakage power compared to bulk MOSFETs. In thin-film (</span><i><span style="font-family:Verdana;">t</span><sub><span style="font-family:Verdana;">si</span></sub></i><span style="font-family:Verdana;"> < 10 nm) DG-MOS structures, charge carriers are affected</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> by</span></span></span><span><span><span style="font-family:""> <i><span style="font-family:Verdana;">t</span><sub><span style="font-family:Verdana;">si</span></sub></i><span style="font-family:Verdana;">-</span></span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">induced quantum confinement along with the confinement caused by </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;">very high electric field at the interface. Therefore, quantum confinement effects on the device characteristics are also quite important and it needs to be incorpo</span><span style="font-family:Verdana;">rated along with short channel effects for nano-scale circuit design. In this</span> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">paper</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">, we analyze</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">d</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> a DG-MOSFET structure at </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">20 nm technology node</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> incorporating quantum confinement effects and various short channel effects. The effect of physical parameter variations on performance characteristics of </span><span><span style="font-family:Verdana;">the device such as threshold voltage, subthreshold slope, </span><i><span style="font-family:Verdana;">I</span><sub><span style="font-family:Verdana;">ON</span></sub></i><span style="font-family:Verdana;"> - </span><i><span style="font-family:Verdana;">I</span><sub><span style="font-family:Verdana;">OFF</span></sub></i><span style="font-family:Verdana;"> ratio,</span></span> <i><span style="font-family:Verdana;">DIBL</span></i></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> etc. has been investigated and plotted through extensive TCAD simulations. The physical parameters considered in this </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">paper</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> are operating temperature </span><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">T</span><sub><span style="font-family:Verdana;">op</span></sub></i><span style="font-family:Verdana;">), channel doping concentration (</span><i><span style="font-family:Verdana;">N</span><sub><span style="font-family:Verdana;">c</span></sub></i><span style="font-family:Verdana;">), gate oxide thickness (</span><i><span style="font-family:Verdana;">t</span><sub><span style="font-family:Verdana;">ox</span></sub></i><span style="font-family:Verdana;">) an</span></span><span style="font-family:Verdana;">d Silicon film thickness (</span><i><span style="font-family:Verdana;">t</span><sub><span style="font-family:Verdana;">si</span></sub></i><span style="font-family:Verdana;">). It </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">was</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> observed that quantum confinement of </span><span style="font-family:Verdana;">charge </span><span style="font-family:Verdana;">carriers significantly affect</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">ed</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the performance characteristics (mostly the</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> subth</span><span style="font-family:Verdana;">reshold characteristics) of the device and therefore, it cannot be ignored in</span><span style="font-family:Verdana;"> the </span><span style="font-family:Verdana;">subthreshold region</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">-</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">based circuit design like in many previous research</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> works. </span><span><span style="font-family:Verdana;">The ATLAS</span><sup><span style="font-family:Verdana;">TM</span></sup><span style="font-family:Verdana;"> device simulator has been used in this </span></span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">paper</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> to perform simu</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">lation and parameter extraction. The TCAD analysis presented in the</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> manuscript can be incorporated for device modeling and device</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> matching. It can be used to illustrate exact device behavior and for proper device control.
文摘A compact model for the integrated inversion charge density Qi in double-gate (DG-) MOSFETs is developed. For nanoscale applications,quantum confinement of the inversion carriers must be taken into account. Based on the previous work of Ge, we establish an expression for the surface potential with respect to Qi, and form an implicit equation, from which Qi can be solved. Results predicted by our model are compared to published data as well as results from Schred,a popular 1D numerical solver that solves the Poisson's and Schr6dinger equa- tions self-consistently. Good agreement is obtained for a wide range of silicon layer thickness,confirming the supe- riority of this model over previous work in this field.
基金supported by the National Basic Research Program of China (2014CB931702)the National Key Research and Development Program of China (2016YFB0401701)+5 种基金the National Natural Science Foundation of China (NSFC 51572128 and 21403109)NSFC-RGC (5151101197)the Natural Science Foundation of Jiangsu Province (BK20160827)China Postdoctoral Science Foundation (2016M590455)the Fundamental Research Funds for the Central Universities (30915012205 and 30916015106)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Quantum confinement effect(QCE), an essential physical phenomenon of semiconductors when the size becomes comparable to the exciton Bohr radius, typically results in quite different physical properties of low-dimensional materials from their bulk counterparts and can be exploited to enhance the device performance in various optoelectronic applications. Here, taking Cs Pb Br3 as an example, we reported QCE in all-inorganic halide perovskite in two-dimensional(2D) nanoplates. Blue shifts in optical absorption and photoluminescence spectra were found to be stronger in thinner nanoplates than that in thicker nanoplates, whose thickness lowered below -7 nm. The exciton binding energy results showed similar trend as that obtained for the optical absorption and photoluminescence. Meanwile, the function of integrated intensity and full width at half maximum and temperature also showed similar results, further supporting our conclusions. The results displayed the QCE in all-inorganic halide perovskite nanoplates and helped to design the all-inorganic halide perovskites with desired optical properties.
基金Project supported by the National Natural Science Foundation of China(Grant No.212731126)the Fundamental Research Program of Shenzhen City,China(Grant Nos.JC201105201112A and JCYJ20120619151629728)the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics,China(Grant No.KF201311)
文摘Silicon nanoparticles have attracted great attention in the past decades because of their intriguing physical properties, active surface state, distinctive photoluminescence and biocompatibility. In this review, we present some of the recent progress in preparation methodologies and surface functionalization approaches of silicon nanoparticles. Further, their promising applications in the fields of energy and electronic engineering are introduced.
文摘The binding energy and effective mass of a polaron confined in a GaAs film deposited on an AlGal-xAs substrate are investigated, for different film thickness values and aluminum concentra- tions and within the framework of the fractional-dimensional space approach. Using this scheme, we propose a new method to define the effective length of the quantum confinement. The limita- tions of the definition of the original effective well width are discussed, and the binding energy and effective mass of a polaron confined in a GaAs film are obtained. The fl-actional-dimensional theo- retical results are shown to be in good agreement with previous, more detailed calculations based on second-order perturbation theory.
基金Natural Foundation of Hebei province, China (Grant 503129 and E2006000999)
文摘Nanocrystalline (nc) 3C-SiC films on the Si substrate were prepared by the helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) technique. With the SiH4-CH4 gas flow ratio changing, the films exhibit different photoluminescence (PL) characteristics. Under the stoichiometric condition, the PL peak redshift from 470 nm to 515 nm is detected with the increase of excitation wavelength, which can be attributed to the quantum confinement effect radiation of 3C-SiC nanocrystals of different sizes. However, the appearance of an additional PL band at 436 nm in Si-rich film might be sourced back to the excess of Si defect centers in it. This is also the case for C-rich film for its PL band lying at 570 nm. The results above quoted indicate an important influence of gas flow ratio on the PL properties of the SiC films providing an effective guidance for analyzing the luminescence mechanism and exploring the high-efficiency light emission of the SiC films.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11264007 and 61465003)
文摘In nanomaterials, optical anisotropies reveal a fundamental relationship between structural and optical properties, in which directional optical properties can be exploited to enhance the performance of optoelectronic devices. First principles calculation based on density functional theory (DFT) with the generalized gradient approximation (GGA) are carried out to investigate the energy band gap structure on silicon (Si) and germanium (Ge) nanofilms. Simulation results show that the band gaps in Si (100) and Ge (111) nanofilms become the direct-gap structure in the thickness range less than 7.64 nm and 7.25 nm respectively, but the band gaps of Si (111) and Ge (110) nanofilms still keep in an indirect-gap structure and are independent on film thickness, and the band gaps of Si (110) and Ge (100) nanofilms could be transferred into the direct-gap structure in nanofilms with smaller thickness. It is amazing that the band gaps of Si(1-x)/ZGexSi(1-x)/2 sandwich structure become the direct-gap structure in a certain area whether (111) or (100) surface. The band structure change of Si and Ge thin films in three orientations is not the same and the physical mechanism is very interesting, where the changes of the band gaps on the Si and Ge nanofilms follow the quantum confinement effects.
文摘Isolated graphene nanoribbons(GNRs)usually have energy gaps,which scale with their widths,owing to the lateral quantum confinement effect of GNRs.The absence of metallic GNRs limits their applications in device interconnects or being one-dimensional physics platform to research amazing properties based on metallicity.A recent study published in Science provided a novel method to produce metallic GNRs by inserting a symmetric superlattice into other semiconductive GNRs.This finding will broader the applications of GNRs both in nanoelectronics and fundamental science.
基金This work was supported by the NationalNatural Science Foundation of China (Grant No. 61675234) and the Advanced Research Foundation of the National University of Defense Technology (Grant No. zk16-03-40).
文摘The quantum confinement effect is important in nanoelectronics and optoelectronics applications; however, there is a discrepancy between the theory of quantum confinement, which indicates that band-gap widening occurs only at small sizes, and experimental observations of band-gap widening in large-diameter nanowires (NWs). This paper reports an obvious blue shift of the absorption edge in the UV-visible absorption spectra of SiC NWs with diameters of 50-300 nm. On the basis of quantum confinement theory and high-resolution transmission electron microscopy images of SiC NWs, band-gap widening in SiC NWs with diameters of up to hundreds of nanometers is fully explained; the results could help to explain similar band-gap widening in other NWs with large diameters.
文摘The growth of nanocrystalline PbS films by chemical bath deposition (CBD) onto glass at temperatureT = 40 ± 2℃, is presented in this research. We report on the modification of structural, optical nanostructures due to in situ Hg-doping.The morphological changes of the layers were analyzed using AFM. XRD spectra displayed peaks at 20 = (26.00, 30.07, 43.10, 51.00, 53.48), indicating growth on the zinc blende face. The grain size determined by x-rays diffraction of the undoped samples, was found -36 nm, whereas with the doped sample was 32-23 nm. Optical absorption, transition direct and indirect the forbidden band gap energy (Eg) shifts discloses a shift in the range 1.45-2.4 eV.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB28000000)the National Natural Science Foundation of China(Grant Nos.61674145,11974340,11434010,11574303,and 11774021)+2 种基金the Ministry of Science and Technology of the People’s Republic of China(Grant Nos.2018YFA0306101,and 2017YFA0303400)the Chinese Academy of Sciences(Grant No.QYZDJSSW-SYS001,and XXH13506-202)the NSFC program for the“Scientific Research Center”(Grant No.U1930402)。
文摘The energy level separation between the edge states in topological insulator quantum dots lies in the terahertz(THz) range.Quantum confinement ensures the nonuniformity of the energy level separation near the Dirac point. Based on these features, we propose that a topological insulator quantum dot array can be operated as an electrically pumped continuous-wave THz laser. The proposed device can operate at room temperature, with power exceeding 10 mW and quantum efficiency reaching ~50%. This study may promote the usage of topological insulator quantum dots as an important source of THz radiation.
基金Acknowledgements This work was supported by the National Basic Research Program of China (Nos. 2013CB632804, 2011CB301900 and 2012CB3155605), the National Natural Science Foundation of China (Grant Nos. 61176015, 61210014, 51002085, 61321004, 61307024 and 61176059), and the High Technology Research and Development Program of China (Nos. 2011AA03Al12, 2011AA03A106, 2011AA03A105 and 2012AA050601).
文摘InGaN quantum dots (QDs) have attracted many research interests in recent years for their potentials to realize long wavelength visible emission from green to red, which can pave a way to fabricate the phosphor-free white light emitting diodes (LEDs). In this paper, we reported our recent progresses on InGaN QD LEDs, the discussions were dedicated to the basic physics model of the strain relaxation in self-assembled InGaN QDs, the growth of InGaN QDs with a growth interruption method by metal organic vapor phase epitaxy, the optimization of GaN barrier growth in multilayer InGaN QDs, the demonstration of green, yellow-green and red InGaN QD LEDs, and future challenges.