GaAs-based nanomaterials are essential for near-infrared nano-photoelectronic devices due to their exceptional optoelectronic properties.However,as the dimensions of GaAs materials decrease,the development of GaAs nan...GaAs-based nanomaterials are essential for near-infrared nano-photoelectronic devices due to their exceptional optoelectronic properties.However,as the dimensions of GaAs materials decrease,the development of GaAs nanowires(NWs)is hindered by type-Ⅱquantum well structures arising from the mixture of zinc blende(ZB)and wurtzite(WZ)phases and surface defects due to the large surface-to-volume ratio.Achieving GaAs-based NWs with high emission efficiency has become a key research focus.In this study,pre-etched silicon substrates were combined with GaAs/AlGaAs core-shell heterostructure to achieve GaAs-based NWs with good perpendicularity,excellent crystal structures,and high emission efficiency by leveraging the shadowing effect and surface passivation.The primary evidence for this includes the prominent free-exciton emission in the variable-temperature spectra and the low thermal activation energy indicated by the variable-power spectra.The findings of this study suggest that the growth method described herein can be employed to enhance the crystal structure and optical properties of otherⅢ-Ⅴlow-dimensional materials,potentially paving the way for future NW devices.展开更多
We have investigated the effect of surface dangling bonds and molecular passivation on the doping of GaAs nanowires by first-principles calculations. Results show that the positively charged surface dangling bond on G...We have investigated the effect of surface dangling bonds and molecular passivation on the doping of GaAs nanowires by first-principles calculations. Results show that the positively charged surface dangling bond on Ga atom is the most stable defect for both ultrathin and large size GaAs nanowires. It can form the trap centers of holes and then prefer to capture the holes from p-type doping. Thus it could obviously reduce the efficiency of the p-type doping. We also found that the NO2 molecule is electronegative enough to capture the unpaired electrons of surface dangling bonds, which is an ideal passivation material for the Zn-doped GaAs nanowires.展开更多
Zinc blende structure GaAs/AlGaAs core-multishell nanowires(NWs)are grown on a GaAs(111)B substrate by a two-temperature process using an Au-catalyzed vapor-liquid-solid mechanism and metal organic chemical vapor depo...Zinc blende structure GaAs/AlGaAs core-multishell nanowires(NWs)are grown on a GaAs(111)B substrate by a two-temperature process using an Au-catalyzed vapor-liquid-solid mechanism and metal organic chemical vapor deposition,respectively.Defect-free radial heterostructure NWs are formed.It can be concluded that the NWs are grown with the main contributions from the direct impingement of the precursors onto the alloy droplets and little from adatom diffusion.The results indicate that the droplet acts as a catalyst rather than an adatom collector.The photoluminescence spectra reveal that the grown NWs have much higher optical efficiency than bare GaAs NWs.展开更多
We investigate the structural phase transitions and electronic properties of GaAs nanowires under high pressure by using synchrotron x-ray diffraction and infrared reflectance spectroscopy methods up to 26.2 GPa at ro...We investigate the structural phase transitions and electronic properties of GaAs nanowires under high pressure by using synchrotron x-ray diffraction and infrared reflectance spectroscopy methods up to 26.2 GPa at room temperature.The zinc-blende to orthorhombic phase transition was observed at around 20.0 GPa.In the same pressure range, pressureinduced metallization of GaAs nanowires was confirmed by infrared reflectance spectra.The metallization originates from the zinc-blende to orthorhombic phase transition.Decompression results demonstrated that the phase transition from zincblende to orthorhombic and the pressure-induced metallization are reversible.Compared to bulk materials, GaAs nanowires show larger bulk modulus and enhanced transition pressure due to the size effects and high surface energy.展开更多
The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires(NWs).We combined three-dimensional(3D)gallium arsenide nanowires with zero-dimensional(0D)WS_(2) quantum ...The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires(NWs).We combined three-dimensional(3D)gallium arsenide nanowires with zero-dimensional(0D)WS_(2) quantum dot(QDs)materials in a simple and convenient way to form a heterogeneous structure.Various performance enhancements have been realized through the formation of typeⅡenergy bands in heterostructures,opening up new research directions for the future development of photodetector devices.This work successfully fabricated a high-sensitivity photodetector based on WS_(2)QDs/GaAs NWs heterostructure.Under 660 nm laser excitation,the photodetector exhibits a responsivity of 368.07 A/W,a detectivity of 2.7×10^(12)Jones,an external quantum efficiency of 6.47×10^(2)%,a low-noise equivalent power of 2.27×10^(-17)W·Hz^(-1/2),a response time of 0.3 s,and a recovery time of 2.12 s.This study provides a new solution for the preparation of high-performance GaAs detectors and promotes the development of optoelectronic devices for GaAs NWs.展开更多
The self-catalyzed growth of Ga As nanowires(NWs)on silicon(Si)is an effective way to achieve integration between group III–V elements and Si.High-crystallinity uniform Ga As NW arrays were grown by solid-source mole...The self-catalyzed growth of Ga As nanowires(NWs)on silicon(Si)is an effective way to achieve integration between group III–V elements and Si.High-crystallinity uniform Ga As NW arrays were grown by solid-source molecular beam epitaxy(MBE).In this paper,we describe systematic experiments which indicate that the substrate treatment is crucial to the highly crystalline and uniform growth of one-dimensional nanomaterials.The influence of natural oxidation time on the crystallinity and uniformity of Ga As NW arrays was investigated and is discussed in detail.The Ga As NW crystallinity and uniformity are maximized after 20 days of natural oxidation time.This work provides a new solution for producing high-crystallinity uniform III–V nanowire arrays on wafer-scale Si substrates.The highly crystalline uniform NW arrays are expected to be useful for NW-based optical interconnects and Si platform optoelectronic devices.展开更多
GaAs nanowires(NWs)are ideal materials for preparing near-infrared photodetectors owing to their high charge carrier mobility and direct band gap.Although the performance of GaAs NW photodetectors can be enhanced by s...GaAs nanowires(NWs)are ideal materials for preparing near-infrared photodetectors owing to their high charge carrier mobility and direct band gap.Although the performance of GaAs NW photodetectors can be enhanced by surface passivation or doping,it still cannot meet the requirement for applications.In this paper we propose a method to greatly improve the performances of GaAs NW photodetectors by hot-hole injection via surface plasmon polaritons.In this case,the responsivity of a single GaAs NW photodetector is increased by a fact of 3.2 to 6.56 A·W^(-1) by attaching capsulelike Au nanoparticles to its surface.This research uses an efficient route to improve the NW photocurrent,which is also important for the development of a high-performance near-infrared NW photodetecor.展开更多
A highly efficient single-photon source based on a semiconductor quantum dot （QD） is a promising candidate in quantum information processing. We report a single-photon source based on self-assembled GaAs QDs in nano...A highly efficient single-photon source based on a semiconductor quantum dot （QD） is a promising candidate in quantum information processing. We report a single-photon source based on self-assembled GaAs QDs in nanowires with an extraction efficiency of 14%. The second-order correlation function g（2） （0） at saturate excitation power is estimated to be 0.28. The measured polarization of QD emission depends on the geometric relations between the directions of PL collection and the long axis of nanowires.展开更多
The first-principles calculations have been performed to determine the effects of Te doping to the structural, electronic, and optical properties of Ga As NWs. The calculated formation energies show that the single Te...The first-principles calculations have been performed to determine the effects of Te doping to the structural, electronic, and optical properties of Ga As NWs. The calculated formation energies show that the single Te energetically prefers to substitute the core Ga（Ef = 0.4111 eV） under As-rich conditions of Ga As nanowires, while on surface, the single Te tends to substitute the surface As site. With increasing the Te concentration, the favorable substitution sites are 2Te–Ga–A and 3Te–Ga–D. Thus, the stability of the structure of the electronic structure and optical properties are discussed.展开更多
Band structure of wurtzite （WZ） GaAs nanowires （NWs） is investigated by using photoluminescenee measurements under hydrostatic pressure at 6 K. We demonstrate that WZ GaAs NWs have a direct bandgap transition with...Band structure of wurtzite （WZ） GaAs nanowires （NWs） is investigated by using photoluminescenee measurements under hydrostatic pressure at 6 K. We demonstrate that WZ GaAs NWs have a direct bandgap transition with an emission energy of 1.53eV, corresponding to the optical transition between conduction band Г7c and valence band Г9v in WZ GaAs. The direct-to-pseudodirect bandgap transition can be observed by applying a pressure approximately above 2.5 GPa.展开更多
Metal–oxide–semiconductor field-effect transistor(MOSFET)faces the major problem of being unable to achieve a subthreshold swing(SS)below 60 mV/dec.As device dimensions continue to reduce and the demand for high swi...Metal–oxide–semiconductor field-effect transistor(MOSFET)faces the major problem of being unable to achieve a subthreshold swing(SS)below 60 mV/dec.As device dimensions continue to reduce and the demand for high switching ratios for low power consumption increases,the tunnel field-effect transistor(TFET)appears to be a viable device,displaying promising characteristic as an answer to the shortcomings of the traditional MOSFET.So far,TFET designing has been a task of sacrificing higher ON state current for low subthreshold swing(and vice versa),and a device that displays both while maintaining structural integrity and operational stability lies in the nascent stages of popular research.This work presents a comprehensive analysis of a heterojunction plasma doped gate-all-around TFET(HPD-GAA-TFET)by making a comparison between Mg_(2)Si and Si which serve as source materials.Charge plasma technique is employed to implement doping in an intrinsic silicon wafer with the help of suitable electrodes.A low-energy bandgap material,i.e.magnesium silicide is incorporated as source material to form a heterojunction between source and silicon-based channel.A rigorous comparison of performance between Si-based GAA-TFET and HPD-GAA-TFET is conducted in terms of electrical,radio frequency(RF),linearity,and distortion parameters.It is observable that HPD-GAA-TFET outperforms conventional Si-based GAA-TFET with an ON-state current(I_(ON)),subthreshold swing(SS),threshold voltage(V_(th)),and current switching ratio being 0.377 mA,12.660 mV/dec,0.214 V,and 2.985×10^(12),respectively.Moreover,HPD-GAA-TFET holds faster switching and is more reliable than Si-based device.Therefore,HPD-GAA-TFET is suitable for low-power applications.展开更多
The steep sub-threshold swing of a tunneling field-effect transistor(TFET)makes it one of the best candidates for lowpower nanometer devices.However,the low driving capability of TFETs prevents their application in in...The steep sub-threshold swing of a tunneling field-effect transistor(TFET)makes it one of the best candidates for lowpower nanometer devices.However,the low driving capability of TFETs prevents their application in integrated circuits.In this study,an innovative gate-all-around(GAA)TFET,which represents a negative capacitance GAA gate-to-source overlap TFET(NCGAA-SOL-TFET),is proposed to increase the driving current.The proposed NCGAA-SOL-TFET is developed based on technology computer-aided design(TCAD)simulations.The proposed structure can solve the problem of the insufficient driving capability of conventional TFETs and is suitable for sub-3-nm nodes.In addition,due to the negative capacitance effect,the surface potential of the channel can be amplified,thus enhancing the driving current.The gateto-source overlap(SOL)technique is used for the first time in an NCGAA-TFET to increase the band-to-band tunneling rate and tunneling area at the silicon-germanium heterojunction.By optimizing the design of the proposed structure via adjusting the SOL length and the ferroelectric layer thickness,a sufficiently large on-state current of 17.20μA can be achieved and the threshold voltage can be reduced to 0.31 V with a sub-threshold swing of 44.98 mV/decade.Finally,the proposed NCGAA-SOL-TFET can overcome the Boltzmann limit-related problem,achieving a driving current that is comparable to that of the traditional complementary metal-oxide semiconductor devices.展开更多
文摘GaAs-based nanomaterials are essential for near-infrared nano-photoelectronic devices due to their exceptional optoelectronic properties.However,as the dimensions of GaAs materials decrease,the development of GaAs nanowires(NWs)is hindered by type-Ⅱquantum well structures arising from the mixture of zinc blende(ZB)and wurtzite(WZ)phases and surface defects due to the large surface-to-volume ratio.Achieving GaAs-based NWs with high emission efficiency has become a key research focus.In this study,pre-etched silicon substrates were combined with GaAs/AlGaAs core-shell heterostructure to achieve GaAs-based NWs with good perpendicularity,excellent crystal structures,and high emission efficiency by leveraging the shadowing effect and surface passivation.The primary evidence for this includes the prominent free-exciton emission in the variable-temperature spectra and the low thermal activation energy indicated by the variable-power spectra.The findings of this study suggest that the growth method described herein can be employed to enhance the crystal structure and optical properties of otherⅢ-Ⅴlow-dimensional materials,potentially paving the way for future NW devices.
基金This work was supported by the National Basic Research Program of China （No.2010CB327600）, the National Natural Science Foundation of China （No.61020106007 and No.61376019）, the Natural Science Foundation of Beijing （No.4142038）, the Specialized Research Fund for the Doctoral Program of Higher Education （No.20120005110011）, and the 111 Program of China （No.B07005）. Jian-gong Cui would like to thank Dr. Xin Yan and Dr. Jun-shuai Li from Beijing University of Posts and Telecommunications for useful discussions.
文摘We have investigated the effect of surface dangling bonds and molecular passivation on the doping of GaAs nanowires by first-principles calculations. Results show that the positively charged surface dangling bond on Ga atom is the most stable defect for both ultrathin and large size GaAs nanowires. It can form the trap centers of holes and then prefer to capture the holes from p-type doping. Thus it could obviously reduce the efficiency of the p-type doping. We also found that the NO2 molecule is electronegative enough to capture the unpaired electrons of surface dangling bonds, which is an ideal passivation material for the Zn-doped GaAs nanowires.
基金Supported by the National Basic Research Program of China under Grant No 2010CB327600the National High Technology R&D Program of China(2009AA03Z417)+2 种基金the National Natural Science Foundation of China(61020106007)New Century Excellent Talents in University(NCET-08-0736)the 111 Program of China(B07005).
文摘Zinc blende structure GaAs/AlGaAs core-multishell nanowires(NWs)are grown on a GaAs(111)B substrate by a two-temperature process using an Au-catalyzed vapor-liquid-solid mechanism and metal organic chemical vapor deposition,respectively.Defect-free radial heterostructure NWs are formed.It can be concluded that the NWs are grown with the main contributions from the direct impingement of the precursors onto the alloy droplets and little from adatom diffusion.The results indicate that the droplet acts as a catalyst rather than an adatom collector.The photoluminescence spectra reveal that the grown NWs have much higher optical efficiency than bare GaAs NWs.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFA0305900)the National Natural Science Foundation of China(Grant No.11604116)+1 种基金Beijing Municipal Natural Science Foundation,China(Grant No.1192017)Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant No.2017156)
文摘We investigate the structural phase transitions and electronic properties of GaAs nanowires under high pressure by using synchrotron x-ray diffraction and infrared reflectance spectroscopy methods up to 26.2 GPa at room temperature.The zinc-blende to orthorhombic phase transition was observed at around 20.0 GPa.In the same pressure range, pressureinduced metallization of GaAs nanowires was confirmed by infrared reflectance spectra.The metallization originates from the zinc-blende to orthorhombic phase transition.Decompression results demonstrated that the phase transition from zincblende to orthorhombic and the pressure-induced metallization are reversible.Compared to bulk materials, GaAs nanowires show larger bulk modulus and enhanced transition pressure due to the size effects and high surface energy.
文摘The performance of the photodetector is significantly impacted by the inherent surface faults in GaAs nanowires(NWs).We combined three-dimensional(3D)gallium arsenide nanowires with zero-dimensional(0D)WS_(2) quantum dot(QDs)materials in a simple and convenient way to form a heterogeneous structure.Various performance enhancements have been realized through the formation of typeⅡenergy bands in heterostructures,opening up new research directions for the future development of photodetector devices.This work successfully fabricated a high-sensitivity photodetector based on WS_(2)QDs/GaAs NWs heterostructure.Under 660 nm laser excitation,the photodetector exhibits a responsivity of 368.07 A/W,a detectivity of 2.7×10^(12)Jones,an external quantum efficiency of 6.47×10^(2)%,a low-noise equivalent power of 2.27×10^(-17)W·Hz^(-1/2),a response time of 0.3 s,and a recovery time of 2.12 s.This study provides a new solution for the preparation of high-performance GaAs detectors and promotes the development of optoelectronic devices for GaAs NWs.
基金the National Natural Science Foundation of China(Grant Nos.61674021,11674038,61704011,61904017,11804335,and 12074045)the Developing Project of Science and Technology of Jilin Province,China(Grant No.20200301052RQ)+1 种基金the Project of Education Department of Jilin Province,China(Grant No.JJKH20200763KJ)the Youth Foundation of Changchun University of Science and Technology(Grant No.XQNJJ-2018-18)。
文摘The self-catalyzed growth of Ga As nanowires(NWs)on silicon(Si)is an effective way to achieve integration between group III–V elements and Si.High-crystallinity uniform Ga As NW arrays were grown by solid-source molecular beam epitaxy(MBE).In this paper,we describe systematic experiments which indicate that the substrate treatment is crucial to the highly crystalline and uniform growth of one-dimensional nanomaterials.The influence of natural oxidation time on the crystallinity and uniformity of Ga As NW arrays was investigated and is discussed in detail.The Ga As NW crystallinity and uniformity are maximized after 20 days of natural oxidation time.This work provides a new solution for producing high-crystallinity uniform III–V nanowire arrays on wafer-scale Si substrates.The highly crystalline uniform NW arrays are expected to be useful for NW-based optical interconnects and Si platform optoelectronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62074018,12074045,61904017and 11804335)the Developing Project of Science and Technology of Jilin Province,China(Grant No.20200301052RQ)the Project of Education Department of Jilin Province,China(Grant Nos.JJKH20200763KJ and JJKH20210831KJ)。
文摘GaAs nanowires(NWs)are ideal materials for preparing near-infrared photodetectors owing to their high charge carrier mobility and direct band gap.Although the performance of GaAs NW photodetectors can be enhanced by surface passivation or doping,it still cannot meet the requirement for applications.In this paper we propose a method to greatly improve the performances of GaAs NW photodetectors by hot-hole injection via surface plasmon polaritons.In this case,the responsivity of a single GaAs NW photodetector is increased by a fact of 3.2 to 6.56 A·W^(-1) by attaching capsulelike Au nanoparticles to its surface.This research uses an efficient route to improve the NW photocurrent,which is also important for the development of a high-performance near-infrared NW photodetecor.
基金Supported by the National Key Basic Research Program of China under Grant No 2013CB922304the National Natural Science Foundation of China under Grant Nos 11474275 and 11204297
文摘A highly efficient single-photon source based on a semiconductor quantum dot （QD） is a promising candidate in quantum information processing. We report a single-photon source based on self-assembled GaAs QDs in nanowires with an extraction efficiency of 14%. The second-order correlation function g（2） （0） at saturate excitation power is estimated to be 0.28. The measured polarization of QD emission depends on the geometric relations between the directions of PL collection and the long axis of nanowires.
基金supported by the Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications,China,No.2012LF1003)the Research Foundation of Education Bureau of Sichuan Province(No.16ZA0316)
文摘The first-principles calculations have been performed to determine the effects of Te doping to the structural, electronic, and optical properties of Ga As NWs. The calculated formation energies show that the single Te energetically prefers to substitute the core Ga（Ef = 0.4111 eV） under As-rich conditions of Ga As nanowires, while on surface, the single Te tends to substitute the surface As site. With increasing the Te concentration, the favorable substitution sites are 2Te–Ga–A and 3Te–Ga–D. Thus, the stability of the structure of the electronic structure and optical properties are discussed.
基金Supported by the National Natural Science Foundation of China under Grant No 11474275
文摘Band structure of wurtzite （WZ） GaAs nanowires （NWs） is investigated by using photoluminescenee measurements under hydrostatic pressure at 6 K. We demonstrate that WZ GaAs NWs have a direct bandgap transition with an emission energy of 1.53eV, corresponding to the optical transition between conduction band Г7c and valence band Г9v in WZ GaAs. The direct-to-pseudodirect bandgap transition can be observed by applying a pressure approximately above 2.5 GPa.
文摘Metal–oxide–semiconductor field-effect transistor(MOSFET)faces the major problem of being unable to achieve a subthreshold swing(SS)below 60 mV/dec.As device dimensions continue to reduce and the demand for high switching ratios for low power consumption increases,the tunnel field-effect transistor(TFET)appears to be a viable device,displaying promising characteristic as an answer to the shortcomings of the traditional MOSFET.So far,TFET designing has been a task of sacrificing higher ON state current for low subthreshold swing(and vice versa),and a device that displays both while maintaining structural integrity and operational stability lies in the nascent stages of popular research.This work presents a comprehensive analysis of a heterojunction plasma doped gate-all-around TFET(HPD-GAA-TFET)by making a comparison between Mg_(2)Si and Si which serve as source materials.Charge plasma technique is employed to implement doping in an intrinsic silicon wafer with the help of suitable electrodes.A low-energy bandgap material,i.e.magnesium silicide is incorporated as source material to form a heterojunction between source and silicon-based channel.A rigorous comparison of performance between Si-based GAA-TFET and HPD-GAA-TFET is conducted in terms of electrical,radio frequency(RF),linearity,and distortion parameters.It is observable that HPD-GAA-TFET outperforms conventional Si-based GAA-TFET with an ON-state current(I_(ON)),subthreshold swing(SS),threshold voltage(V_(th)),and current switching ratio being 0.377 mA,12.660 mV/dec,0.214 V,and 2.985×10^(12),respectively.Moreover,HPD-GAA-TFET holds faster switching and is more reliable than Si-based device.Therefore,HPD-GAA-TFET is suitable for low-power applications.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(Grant No.LY22F040001)the National Natural Science Foundation of China(Grant No.62071160)the Graduate Scientific Research Foundation of Hangzhou Dianzi University。
文摘The steep sub-threshold swing of a tunneling field-effect transistor(TFET)makes it one of the best candidates for lowpower nanometer devices.However,the low driving capability of TFETs prevents their application in integrated circuits.In this study,an innovative gate-all-around(GAA)TFET,which represents a negative capacitance GAA gate-to-source overlap TFET(NCGAA-SOL-TFET),is proposed to increase the driving current.The proposed NCGAA-SOL-TFET is developed based on technology computer-aided design(TCAD)simulations.The proposed structure can solve the problem of the insufficient driving capability of conventional TFETs and is suitable for sub-3-nm nodes.In addition,due to the negative capacitance effect,the surface potential of the channel can be amplified,thus enhancing the driving current.The gateto-source overlap(SOL)technique is used for the first time in an NCGAA-TFET to increase the band-to-band tunneling rate and tunneling area at the silicon-germanium heterojunction.By optimizing the design of the proposed structure via adjusting the SOL length and the ferroelectric layer thickness,a sufficiently large on-state current of 17.20μA can be achieved and the threshold voltage can be reduced to 0.31 V with a sub-threshold swing of 44.98 mV/decade.Finally,the proposed NCGAA-SOL-TFET can overcome the Boltzmann limit-related problem,achieving a driving current that is comparable to that of the traditional complementary metal-oxide semiconductor devices.
