Effects of nonparabolicity of energy band on thermopower, in-plane effective mass and Fermi energy are inves- tigated in size-quantized semiconductor films in a strong while non-quantized magnetic field. We obtain the...Effects of nonparabolicity of energy band on thermopower, in-plane effective mass and Fermi energy are inves- tigated in size-quantized semiconductor films in a strong while non-quantized magnetic field. We obtain the expressions of these quantities as functions of thickness, concentration and nonparabolicity parameter. The influence of nonparabolicity is studied for degenerate and non-degenerate electron gases, and it is shown that nonparabolicity changes the character of thickness and the concentration dependence of thermopower, in-plane effective mass and Fermi energy. Moreover, the magnitudes of these quantities significantly increase with respect to the nonparabolicity parameter in the case of strong nonparabolicity in nano-films. The concentration depen- dence is also studied, and it is shown that thermopower increases when the concentration decreases. These results are in agreement with the experimental data.展开更多
Ultraviolet(UV) photodetectors have attracted more and more attention due to their great potential applications in missile tracking, flame detecting, pollution monitoring, ozone layer monitoring, and so on. Owing to t...Ultraviolet(UV) photodetectors have attracted more and more attention due to their great potential applications in missile tracking, flame detecting, pollution monitoring, ozone layer monitoring, and so on. Owing to the special characteristics of large bandgap, solution processable, low cost, environmentally friendly, etc., wide bandgap oxide semiconductor materials, such as ZnO, ZnMgO, Ga_2O_3, TiO_2, and Ni O, have gradually become a series of star materials in the field of semiconductor UV detection. In this paper, a review is presented on the development of UV photodetectors based on wide bandgap oxide semiconductor films.展开更多
The kinetics of interracial processes of CdSe thin film electrode before and after sur- face modification of 1,1'-di linolene ferrocenyl L-B films have been studied in K_4Fe(CN)_6 solution by Intensity Modulated P...The kinetics of interracial processes of CdSe thin film electrode before and after sur- face modification of 1,1'-di linolene ferrocenyl L-B films have been studied in K_4Fe(CN)_6 solution by Intensity Modulated Photocurrent Spectroscopy(IMPS).Potential dependence of surface state relaxation time(T_s),steady state photocurrent(I_s),collection coefficient of minority carriers(G_o), rate constant of photocorrosion(K_(cr)),and density of surface state(N_(ss))were determined in terms of frequency response analysis of IMPS plots.展开更多
This paper derives the expressions for the ordering degree and the modulation factor of A and B atoms in AXB1-xC epilayers of ternary III-V semiconductor alloys. Using these expressions, it identifies quantitatively t...This paper derives the expressions for the ordering degree and the modulation factor of A and B atoms in AXB1-xC epilayers of ternary III-V semiconductor alloys. Using these expressions, it identifies quantitatively the alternating atom-enhanced planes, compositional modulations, atomic ordering degree on the group-III sublattices and the fine structure of NMR spectra.展开更多
Alternating current（AC） conductivity and dielectric properties of thermally evaporated Au/Pt OEP/Au thin films are investigated each as a function of temperature（303 K–473 K） and frequency（50 Hz–5 MHz）.The fre...Alternating current（AC） conductivity and dielectric properties of thermally evaporated Au/Pt OEP/Au thin films are investigated each as a function of temperature（303 K–473 K） and frequency（50 Hz–5 MHz）.The frequency dependence of AC conductivity follows the Jonscher universal dynamic law.The AC-activation energies are determined at different frequencies.It is found that the correlated barrier hopping（CBH） model is the dominant conduction mechanism.The variation of the frequency exponent s with temperature is analyzed in terms of the CBH model.Coulombic barrier height Wm,hopping distance Rω,and the density of localized states N（EF） are valued at different frequencies.Dielectric constant ε1（ω,T） and dielectric loss ε2（ω,T） are discussed in terms of the dielectric polarization process.The dielectric modulus shows the non-Debye relaxation in the material.The extracted relaxation time by using the imaginary part of modulus（M’’）is found to follow the Arrhenius law.展开更多
Hexagonal gallium nitride films were successfully fabricated throughammoniating Ga_2O_3 films deposited on silicon (111) substrates by electrophoresis. The structure,composition, and surface morphology of the formed f...Hexagonal gallium nitride films were successfully fabricated throughammoniating Ga_2O_3 films deposited on silicon (111) substrates by electrophoresis. The structure,composition, and surface morphology of the formed films were characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmissionelectron microscopy (TEM). The measurement results reveal that the polycrystalline GaN films withhexagonal wurtzite structure were successfully grown on the silicon (111) substrates. Preliminaryresults suggest that varying the ammoniating temperature has obvious effect on the quality of theGaN films formed with this method.展开更多
Visible photoluminescence （PL） has been observed from rare earth （Tm, Sm and Dy）-doped AlN films grown by radio-frequency magnetron reactive sputtering. X-ray diffraction indicates that the films are c-axis-orient...Visible photoluminescence （PL） has been observed from rare earth （Tm, Sm and Dy）-doped AlN films grown by radio-frequency magnetron reactive sputtering. X-ray diffraction indicates that the films are c-axis-oriented hexagonal wurtzite type structure with an average crystal size of about 80-110 nm. Room-temperature PL spectra indicate that the blue emission is due to the transition of ^1D2 to ^3F4 and ^1G4 to ^3H6 intra 4f electron of Tm^3＋, the yellow emissions of AlN：Sm are due to ^4G5/2 to the ^6HJ （J=5/2, 7/2, 9/2, 11/2） and the reddish emissions of AlN：Dy correspond to the ^4F9/2 to ^6HJ （J=5/2, 13/2, 11/2 and 9/2） and ^6Fll/2 transitions.展开更多
A chemical vapour deposition （CVD） diamond film detector was prepared and the main characteristics for pulsed proton detection were studied at Beijing Tandem Accelerator. The result shows that the charge collection ...A chemical vapour deposition （CVD） diamond film detector was prepared and the main characteristics for pulsed proton detection were studied at Beijing Tandem Accelerator. The result shows that the charge collection efficiency of the detector increases with increasing electric field intensity and reaches to 9.44% at 5 V/μm with the charge collection distance of 15.9 μm. The relationship between the sensitivity of the detector and proton energy is consistent with the Monte Carlo （MC） simulation result. Its plasma time for a pulse with 4.85×10^5 protons is 1l.2ns. The dose threshold for onset of damage under 9MeV proton irradiation in the detector is about 10^13 cm^-2. All of the results show that a CVD diamond detector has fast time response and high radiation hardness, and can be used in pulsed proton detection.展开更多
ZnO/CdO composite films with different CdO contents are obtained by pulse laser deposition technique. The structural, optical and electrical properties of the composite [liras are investigated by x-ray diffraction, ph...ZnO/CdO composite films with different CdO contents are obtained by pulse laser deposition technique. The structural, optical and electrical properties of the composite [liras are investigated by x-ray diffraction, photolu- minescence and electrical resistivity measurements, respectively. The results show that the UV emission is at a constant peak position in the photoluminescence spectra. Meanwhile, their electrical resistivity decreases to very low level approaching to the value of the CdO film, which can be explained by the Matthiessen composite rule for resistivity. The peculiarity of low resistivity and high transnlittance in the visible region enables these Rims suitable for optoelectronic device fabrication.展开更多
ZnO thin films were deposited on n-Si （111） at various substrate temperatures by pulsed laser deposition （PLD）. X-ray diffraction （XRD）, photoluminescence （PL）, Fourier transform infrared spectrophotometer （F...ZnO thin films were deposited on n-Si （111） at various substrate temperatures by pulsed laser deposition （PLD）. X-ray diffraction （XRD）, photoluminescence （PL）, Fourier transform infrared spectrophotometer （FTIR）, and scanning electron microscopy （SEM） were used to analyze the structure, morphology, and optical property of the ZnO thin films. An optimal crystallized ZnO thin film was obtained at the substrate temperature of 600℃. A blue shift was found in PL spectra due to size confinement effect as the grain sizes decreased. The surfaces of the ZnO thin films were more planar and compact as the substrate temperature increased.展开更多
文摘Effects of nonparabolicity of energy band on thermopower, in-plane effective mass and Fermi energy are inves- tigated in size-quantized semiconductor films in a strong while non-quantized magnetic field. We obtain the expressions of these quantities as functions of thickness, concentration and nonparabolicity parameter. The influence of nonparabolicity is studied for degenerate and non-degenerate electron gases, and it is shown that nonparabolicity changes the character of thickness and the concentration dependence of thermopower, in-plane effective mass and Fermi energy. Moreover, the magnitudes of these quantities significantly increase with respect to the nonparabolicity parameter in the case of strong nonparabolicity in nano-films. The concentration depen- dence is also studied, and it is shown that thermopower increases when the concentration decreases. These results are in agreement with the experimental data.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61475153 and 61605200)the Jilin Province Young and Middle-aged Science and Technology Innovation Leaders and Team Project,China(Grant No.20180519023JH)+1 种基金the 100 Talents Program of the Chinese Academy of Sciencesthe Science Fund for Excellent Young Scholars of Jilin Province,China(Grant No.20180520173JH)
文摘Ultraviolet(UV) photodetectors have attracted more and more attention due to their great potential applications in missile tracking, flame detecting, pollution monitoring, ozone layer monitoring, and so on. Owing to the special characteristics of large bandgap, solution processable, low cost, environmentally friendly, etc., wide bandgap oxide semiconductor materials, such as ZnO, ZnMgO, Ga_2O_3, TiO_2, and Ni O, have gradually become a series of star materials in the field of semiconductor UV detection. In this paper, a review is presented on the development of UV photodetectors based on wide bandgap oxide semiconductor films.
基金This work was supported by the National Natural Science Foundation of China
文摘The kinetics of interracial processes of CdSe thin film electrode before and after sur- face modification of 1,1'-di linolene ferrocenyl L-B films have been studied in K_4Fe(CN)_6 solution by Intensity Modulated Photocurrent Spectroscopy(IMPS).Potential dependence of surface state relaxation time(T_s),steady state photocurrent(I_s),collection coefficient of minority carriers(G_o), rate constant of photocorrosion(K_(cr)),and density of surface state(N_(ss))were determined in terms of frequency response analysis of IMPS plots.
基金Project supported by the National Natural Science Foundation of China (Grant No 60572177)CAUC Foundation (Grant No 05yk27s)
文摘This paper derives the expressions for the ordering degree and the modulation factor of A and B atoms in AXB1-xC epilayers of ternary III-V semiconductor alloys. Using these expressions, it identifies quantitatively the alternating atom-enhanced planes, compositional modulations, atomic ordering degree on the group-III sublattices and the fine structure of NMR spectra.
文摘Alternating current（AC） conductivity and dielectric properties of thermally evaporated Au/Pt OEP/Au thin films are investigated each as a function of temperature（303 K–473 K） and frequency（50 Hz–5 MHz）.The frequency dependence of AC conductivity follows the Jonscher universal dynamic law.The AC-activation energies are determined at different frequencies.It is found that the correlated barrier hopping（CBH） model is the dominant conduction mechanism.The variation of the frequency exponent s with temperature is analyzed in terms of the CBH model.Coulombic barrier height Wm,hopping distance Rω,and the density of localized states N（EF） are valued at different frequencies.Dielectric constant ε1（ω,T） and dielectric loss ε2（ω,T） are discussed in terms of the dielectric polarization process.The dielectric modulus shows the non-Debye relaxation in the material.The extracted relaxation time by using the imaginary part of modulus（M’’）is found to follow the Arrhenius law.
基金This work is financially supported by the Key Research Program of National Natural Science Foundation of China (No. 90201025)the National Natural Science Foundation of China (No. 60071006)
文摘Hexagonal gallium nitride films were successfully fabricated throughammoniating Ga_2O_3 films deposited on silicon (111) substrates by electrophoresis. The structure,composition, and surface morphology of the formed films were characterized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmissionelectron microscopy (TEM). The measurement results reveal that the polycrystalline GaN films withhexagonal wurtzite structure were successfully grown on the silicon (111) substrates. Preliminaryresults suggest that varying the ammoniating temperature has obvious effect on the quality of theGaN films formed with this method.
基金Project supported by the National Natural Science Foundation of China （Grant No 50372082）.
文摘Visible photoluminescence （PL） has been observed from rare earth （Tm, Sm and Dy）-doped AlN films grown by radio-frequency magnetron reactive sputtering. X-ray diffraction indicates that the films are c-axis-oriented hexagonal wurtzite type structure with an average crystal size of about 80-110 nm. Room-temperature PL spectra indicate that the blue emission is due to the transition of ^1D2 to ^3F4 and ^1G4 to ^3H6 intra 4f electron of Tm^3＋, the yellow emissions of AlN：Sm are due to ^4G5/2 to the ^6HJ （J=5/2, 7/2, 9/2, 11/2） and the reddish emissions of AlN：Dy correspond to the ^4F9/2 to ^6HJ （J=5/2, 13/2, 11/2 and 9/2） and ^6Fll/2 transitions.
基金Project supported by the National Natural Science Foundation of China (Grant No 10675074)
文摘A chemical vapour deposition （CVD） diamond film detector was prepared and the main characteristics for pulsed proton detection were studied at Beijing Tandem Accelerator. The result shows that the charge collection efficiency of the detector increases with increasing electric field intensity and reaches to 9.44% at 5 V/μm with the charge collection distance of 15.9 μm. The relationship between the sensitivity of the detector and proton energy is consistent with the Monte Carlo （MC） simulation result. Its plasma time for a pulse with 4.85×10^5 protons is 1l.2ns. The dose threshold for onset of damage under 9MeV proton irradiation in the detector is about 10^13 cm^-2. All of the results show that a CVD diamond detector has fast time response and high radiation hardness, and can be used in pulsed proton detection.
基金Supported by the National Nature Science Foundation under Grant No 50871046, the National Basic Research Program of China under Grant No 2010CB631001, and the Program for Changjiang Scholars and Innovative Research Team in University.
文摘ZnO/CdO composite films with different CdO contents are obtained by pulse laser deposition technique. The structural, optical and electrical properties of the composite [liras are investigated by x-ray diffraction, photolu- minescence and electrical resistivity measurements, respectively. The results show that the UV emission is at a constant peak position in the photoluminescence spectra. Meanwhile, their electrical resistivity decreases to very low level approaching to the value of the CdO film, which can be explained by the Matthiessen composite rule for resistivity. The peculiarity of low resistivity and high transnlittance in the visible region enables these Rims suitable for optoelectronic device fabrication.
基金This work was financially supported by the Key Research Program of National Natural Science Foundation of China (No. 90301002 and No. 90201025)
文摘ZnO thin films were deposited on n-Si （111） at various substrate temperatures by pulsed laser deposition （PLD）. X-ray diffraction （XRD）, photoluminescence （PL）, Fourier transform infrared spectrophotometer （FTIR）, and scanning electron microscopy （SEM） were used to analyze the structure, morphology, and optical property of the ZnO thin films. An optimal crystallized ZnO thin film was obtained at the substrate temperature of 600℃. A blue shift was found in PL spectra due to size confinement effect as the grain sizes decreased. The surfaces of the ZnO thin films were more planar and compact as the substrate temperature increased.
