In this paper, the positive influence of a uni-traveling-carrier （UTC） structure to ease the contract between the respon- sivity and working speed of the InP-based double hetero-junction phototransistor （DHPT） is ...In this paper, the positive influence of a uni-traveling-carrier （UTC） structure to ease the contract between the respon- sivity and working speed of the InP-based double hetero-junction phototransistor （DHPT） is illustrated in detail. Different results under electrical bias, optical bias or combined electrical and optical bias are analyzed for an excellent UTC-DHPT performance. The results show that when the UTC-DHPT operates at three-terminal （3T） working mode with combined electrical bias and optical bias in base, it keeps a high optical responsivity of 34.72 A/W and the highest optical transition frequency of 120 GHz. The current gain of the 3T UTC-DHPT under 1.55-μm light illuminations reaches 62 dB. This indicates that the combined base electrical bias and optical bias of 3T UTC-DHPT can make sure that the UTC-DHPT provides high optical current gain and high optical transition frequency simultaneously.展开更多
Positron annihilation spectroscopy on GaN films grown on SiC substrate with MBE are presented. It is shown that the GaN/SiC interface is rectifying towards positrons, such that positrons can only travel from SiC to Ga...Positron annihilation spectroscopy on GaN films grown on SiC substrate with MBE are presented. It is shown that the GaN/SiC interface is rectifying towards positrons, such that positrons can only travel from SiC to GaN and not vice versa. Potential steps seen by the positron at the GaN/SiC interface are calculated from experimental values of electron and positron work function. This “rectifying” effect has been successfully mimicked by inserting a thin region of very high electric field in the Variable Energy Positron Fit （VEPF） analysis. The built-in electric field is attributed to different positron affinities, dislocation and/or interface defects at the GaN/SiC interface.展开更多
A fully-coupled model for a piezoelectric hetero-junction subjected to a pair of stresses is proposed by discarding the depletion layer approximation.The effect of mechanical loadings on PN junction performance is dis...A fully-coupled model for a piezoelectric hetero-junction subjected to a pair of stresses is proposed by discarding the depletion layer approximation.The effect of mechanical loadings on PN junction performance is discussed in detail.Numerical examples are carried out for a p-Si/ZnO-n hetero-junction under a pair of stresses acting on the ntype ZnO portion near the PN interface,where ZnO has the piezoelectric property while Si is not.It is found that the bottom of conduction band is lowered/raised near the two loading points due to the decrease/increase in the electron potential energy there induced by a tensile-stress mode via sucking in majority-carriers from two outside regions,which implies appearance of a potential barrier and a potential well near two loading points.Furthermore,the barrier height and well depth gradually become large with increasing tensile stress such that more and more electrons/holes are inhaled in loading region from the n-/p-zone,respectively.Conversely,rising/dropping of conduction band bottom is brought out near the two loading points by a compressive-stress mode due to the increase/decrease in the potential energy of electrons by pumping out the majority-carriers from the loading region to the two outside regions.Therefore,a potential well and a potential barrier are induced near the two loading points,such that more and more electrons/holes are driven away from the loading region to the n-zone/p-zone,respectively,with the increasing compressive stress.These effects are important to tune the carrier recombination rate near the PN interface.Thus,the present study possesses great referential significance to piezotronic devices.展开更多
The paper reported the design and thorough analysis of a thin-film solar cell (TFSC) based on molybdenum disulfide (MoS<sub>2</sub>) with an integrated Copper(I) Oxide (Cu<sub>2</sub>O) hole tr...The paper reported the design and thorough analysis of a thin-film solar cell (TFSC) based on molybdenum disulfide (MoS<sub>2</sub>) with an integrated Copper(I) Oxide (Cu<sub>2</sub>O) hole transport layer (HTL), employing the one-dimensional Solar Cell Capacitance Simulator (SCAPS-1D) software. By varying crucial parameters such as absorber layer thickness, doping density, and bulk defect density, as well as HTL thickness, doping concentration, and electron affinity, defect density at ZnO/absorber and absorber/Cu<sub>2</sub>O interfaces, and operating temperature, we explored key photovoltaic measures including open circuit voltage (Voc), short-circuit current density (Jsc), fill-factor (FF), and power conversion efficiency (PCE) of the hetero-junction solar cell. The study demonstrated an efficiency of 18.87% for the MoS<sub>2</sub> solar cell without HTL, while the proposed solar cell (SC) utilizing Cu<sub>2</sub>O HTL and optimized device structure exhibited a remarkable PCE of 26.70%. The outcomes derived from the present study offer valuable insights for the progress of a highly efficient and economically viable MoS<sub>2</sub> hetero-junction TFSC.展开更多
A set of forty-three hetero-junction CNTs, made of forty-four homogeneous carbon nanotubes of different chiralities and configurations with all possible hetero-connection types, were numerically simulated, based on th...A set of forty-three hetero-junction CNTs, made of forty-four homogeneous carbon nanotubes of different chiralities and configurations with all possible hetero-connection types, were numerically simulated, based on the finite element method in a commercial finite element software and their Young's and shear moduli, and critical buckling loads were obtained and evaluated under the tensile, torsional and buckling loads with an assumption of linear elastic deformation and also compared with each other. The comparison of the linear elastic behavior of hetero-junction CNTs and their corresponding fundamental tubes revealed that the size, type of the connection, and the bending angle in the structure of hetero-junction CNTs considerably influences the mechanical properties of these hetero-structures. It was also discovered that the Stone-Wales defect leads to lower elastic and torsional strength of hetero-junction CNTs when compared to homogeneous CNTs. However, the buckling strength of the hetero-junction CNTs was found to lie in the range of the buckling strength of their corresponding fundamental tubes. It was also determined that the shear modulus of hetero-junction carbon nanotubes generally tends to be closer to the shear modulus of their wider fundamental tubes while critical buckling loads of these heterostructures seem to be closer to critical buckling loads of their thinner fundamental tubes. The evaluation of the elastic properties of hetero-junction carbon nanotubes showed that among the hetero-junction models, those with armchair-armchair and zigzag-zigzag kinks have the highest elastic modulus while the models with armchair-zigzag connections show the lowest elastic stiffness. The results from torsion tests also revealed the fact that zigzag-zigzag and armchair-zigzag hetero-junction carbon nanotubes have the highest and the lowest shear modulus, respectively. Finally, it was observed that the highest critical buckling loads belong to armchair-armchair hetero-junction carbon nanotubes and the lowest buckling strength was found with the hetero-junction models with armchair-zigzag connection.展开更多
A hetero-junction of n-silicon（n-Si） and copper phthalocyanine（CuPc） has been fabricated.The current -voltage characteristics were investigated to explain the rectification and conduction mechanism.The effect of t...A hetero-junction of n-silicon（n-Si） and copper phthalocyanine（CuPc） has been fabricated.The current -voltage characteristics were investigated to explain the rectification and conduction mechanism.The effect of temperature and humidity on the electrical properties of n-Si/CuPc hetero-junction has also been investigated.The characteristics of the junction have been observed to be temperature and humidity dependent,so it is suggested that this junction can be used as a temperature and humidity sensor.展开更多
A light-activated Darlington heterojunction transistor based on a SiCGe/3C-SiC hetero-structure is proposed for anti-EMI（electromagnetic interference） applications. The performance of the novel power switch is simul...A light-activated Darlington heterojunction transistor based on a SiCGe/3C-SiC hetero-structure is proposed for anti-EMI（electromagnetic interference） applications. The performance of the novel power switch is simulated using ISE. In comparison with the switches based on other polytypes of SiC,the design benefits from having fewer lattice mismatches between the SiCGe and 3C-SiC. A maximum common emitter current gain of about 890 and superb light-activation characteristics may be achievable. The performance simulation demonstrates that the device has a good I-V characteristic with a turn-on voltage knee of about 4V.展开更多
An anodic TiO2/g-C3N4 hetero-junction and cathodic WO3/W were used to build a self-sustained catalytic fuel cell system for oxidizing rhodamine B or triclosan and reducing NO3^--N to N2 simultaneously.The WO3 nano-cat...An anodic TiO2/g-C3N4 hetero-junction and cathodic WO3/W were used to build a self-sustained catalytic fuel cell system for oxidizing rhodamine B or triclosan and reducing NO3^--N to N2 simultaneously.The WO3 nano-catalyst was formed in situ by heating and oxidizing a tungsten wire in air.Cyclic voltammetry and current-time curves were used to characterize the electrochemical properties of the electrodes and system.Aeration and activation of molecular oxygen by self-biased TiO2/g-C3N4 led to the formation of reactive oxidizing species in the fuel cell.The mechanism of simultaneous anodic oxidation of pollutants and cathodic reduction of nitrate was proposed.The spontaneously formed circuit and tiny current were used simultaneously in treating two kinds of wastewater in the reactor chambers,even without light illumination or an external applied voltage.This new catalytic pollution control route can lower energy consumption and degrade many other kinds of pollutants.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61006044)the Natural Science Foundation of Beijing,China(Grant Nos.4122014 and 4142007)the Fund from the Beijing Municipal Education Committee,China(Grant No.KM200910005001)
文摘In this paper, the positive influence of a uni-traveling-carrier （UTC） structure to ease the contract between the respon- sivity and working speed of the InP-based double hetero-junction phototransistor （DHPT） is illustrated in detail. Different results under electrical bias, optical bias or combined electrical and optical bias are analyzed for an excellent UTC-DHPT performance. The results show that when the UTC-DHPT operates at three-terminal （3T） working mode with combined electrical bias and optical bias in base, it keeps a high optical responsivity of 34.72 A/W and the highest optical transition frequency of 120 GHz. The current gain of the 3T UTC-DHPT under 1.55-μm light illuminations reaches 62 dB. This indicates that the combined base electrical bias and optical bias of 3T UTC-DHPT can make sure that the UTC-DHPT provides high optical current gain and high optical transition frequency simultaneously.
文摘Positron annihilation spectroscopy on GaN films grown on SiC substrate with MBE are presented. It is shown that the GaN/SiC interface is rectifying towards positrons, such that positrons can only travel from SiC to GaN and not vice versa. Potential steps seen by the positron at the GaN/SiC interface are calculated from experimental values of electron and positron work function. This “rectifying” effect has been successfully mimicked by inserting a thin region of very high electric field in the Variable Energy Positron Fit （VEPF） analysis. The built-in electric field is attributed to different positron affinities, dislocation and/or interface defects at the GaN/SiC interface.
基金Project supported by the National Natural Science Foundation of China(Nos.11972164 and 12102141)。
文摘A fully-coupled model for a piezoelectric hetero-junction subjected to a pair of stresses is proposed by discarding the depletion layer approximation.The effect of mechanical loadings on PN junction performance is discussed in detail.Numerical examples are carried out for a p-Si/ZnO-n hetero-junction under a pair of stresses acting on the ntype ZnO portion near the PN interface,where ZnO has the piezoelectric property while Si is not.It is found that the bottom of conduction band is lowered/raised near the two loading points due to the decrease/increase in the electron potential energy there induced by a tensile-stress mode via sucking in majority-carriers from two outside regions,which implies appearance of a potential barrier and a potential well near two loading points.Furthermore,the barrier height and well depth gradually become large with increasing tensile stress such that more and more electrons/holes are inhaled in loading region from the n-/p-zone,respectively.Conversely,rising/dropping of conduction band bottom is brought out near the two loading points by a compressive-stress mode due to the increase/decrease in the potential energy of electrons by pumping out the majority-carriers from the loading region to the two outside regions.Therefore,a potential well and a potential barrier are induced near the two loading points,such that more and more electrons/holes are driven away from the loading region to the n-zone/p-zone,respectively,with the increasing compressive stress.These effects are important to tune the carrier recombination rate near the PN interface.Thus,the present study possesses great referential significance to piezotronic devices.
文摘The paper reported the design and thorough analysis of a thin-film solar cell (TFSC) based on molybdenum disulfide (MoS<sub>2</sub>) with an integrated Copper(I) Oxide (Cu<sub>2</sub>O) hole transport layer (HTL), employing the one-dimensional Solar Cell Capacitance Simulator (SCAPS-1D) software. By varying crucial parameters such as absorber layer thickness, doping density, and bulk defect density, as well as HTL thickness, doping concentration, and electron affinity, defect density at ZnO/absorber and absorber/Cu<sub>2</sub>O interfaces, and operating temperature, we explored key photovoltaic measures including open circuit voltage (Voc), short-circuit current density (Jsc), fill-factor (FF), and power conversion efficiency (PCE) of the hetero-junction solar cell. The study demonstrated an efficiency of 18.87% for the MoS<sub>2</sub> solar cell without HTL, while the proposed solar cell (SC) utilizing Cu<sub>2</sub>O HTL and optimized device structure exhibited a remarkable PCE of 26.70%. The outcomes derived from the present study offer valuable insights for the progress of a highly efficient and economically viable MoS<sub>2</sub> hetero-junction TFSC.
文摘A set of forty-three hetero-junction CNTs, made of forty-four homogeneous carbon nanotubes of different chiralities and configurations with all possible hetero-connection types, were numerically simulated, based on the finite element method in a commercial finite element software and their Young's and shear moduli, and critical buckling loads were obtained and evaluated under the tensile, torsional and buckling loads with an assumption of linear elastic deformation and also compared with each other. The comparison of the linear elastic behavior of hetero-junction CNTs and their corresponding fundamental tubes revealed that the size, type of the connection, and the bending angle in the structure of hetero-junction CNTs considerably influences the mechanical properties of these hetero-structures. It was also discovered that the Stone-Wales defect leads to lower elastic and torsional strength of hetero-junction CNTs when compared to homogeneous CNTs. However, the buckling strength of the hetero-junction CNTs was found to lie in the range of the buckling strength of their corresponding fundamental tubes. It was also determined that the shear modulus of hetero-junction carbon nanotubes generally tends to be closer to the shear modulus of their wider fundamental tubes while critical buckling loads of these heterostructures seem to be closer to critical buckling loads of their thinner fundamental tubes. The evaluation of the elastic properties of hetero-junction carbon nanotubes showed that among the hetero-junction models, those with armchair-armchair and zigzag-zigzag kinks have the highest elastic modulus while the models with armchair-zigzag connections show the lowest elastic stiffness. The results from torsion tests also revealed the fact that zigzag-zigzag and armchair-zigzag hetero-junction carbon nanotubes have the highest and the lowest shear modulus, respectively. Finally, it was observed that the highest critical buckling loads belong to armchair-armchair hetero-junction carbon nanotubes and the lowest buckling strength was found with the hetero-junction models with armchair-zigzag connection.
文摘A hetero-junction of n-silicon（n-Si） and copper phthalocyanine（CuPc） has been fabricated.The current -voltage characteristics were investigated to explain the rectification and conduction mechanism.The effect of temperature and humidity on the electrical properties of n-Si/CuPc hetero-junction has also been investigated.The characteristics of the junction have been observed to be temperature and humidity dependent,so it is suggested that this junction can be used as a temperature and humidity sensor.
文摘A light-activated Darlington heterojunction transistor based on a SiCGe/3C-SiC hetero-structure is proposed for anti-EMI（electromagnetic interference） applications. The performance of the novel power switch is simulated using ISE. In comparison with the switches based on other polytypes of SiC,the design benefits from having fewer lattice mismatches between the SiCGe and 3C-SiC. A maximum common emitter current gain of about 890 and superb light-activation characteristics may be achievable. The performance simulation demonstrates that the device has a good I-V characteristic with a turn-on voltage knee of about 4V.
基金supported by the National Natural Science Foundation of China (21177018, 21677025)the Program of Introducing Talents of Discipline to Universities (B13012)~~
文摘An anodic TiO2/g-C3N4 hetero-junction and cathodic WO3/W were used to build a self-sustained catalytic fuel cell system for oxidizing rhodamine B or triclosan and reducing NO3^--N to N2 simultaneously.The WO3 nano-catalyst was formed in situ by heating and oxidizing a tungsten wire in air.Cyclic voltammetry and current-time curves were used to characterize the electrochemical properties of the electrodes and system.Aeration and activation of molecular oxygen by self-biased TiO2/g-C3N4 led to the formation of reactive oxidizing species in the fuel cell.The mechanism of simultaneous anodic oxidation of pollutants and cathodic reduction of nitrate was proposed.The spontaneously formed circuit and tiny current were used simultaneously in treating two kinds of wastewater in the reactor chambers,even without light illumination or an external applied voltage.This new catalytic pollution control route can lower energy consumption and degrade many other kinds of pollutants.
