Three samples of GaAs/A1As multiple-quantum wells with different quantum well widths and tS-doped with Be ac- ceptors at the well center were grown on （100） GaAs substrates by molecular beam epitaxy. Polarized Raman...Three samples of GaAs/A1As multiple-quantum wells with different quantum well widths and tS-doped with Be ac- ceptors at the well center were grown on （100） GaAs substrates by molecular beam epitaxy. Polarized Raman spectra were recorded on the three samples at temperatures in a range of 4-50 K in a backscattering configuration. The two branches of coupled modes due to the interaction of the hole intersubband transitions and the quantum-well longitudinal optical （LO） phonon were observed clearly. The evaluation formalism of the Green function was employed and each lineshape of the Raman spectrum of the coupled modes was simulated. The dependence of the peak position of Raman shifts of the two coupled modes as well as the quantum-well LO phonon on the quantum-well size and measured temperature were given, and the coupling interaction mechanism between the hole subband transitions and the quantum-well LO phonon was researched.展开更多
A series of GaAs/A1As multiple-quantum wells doped with Be is grown by molecular beam epitaxy. The photolu- minescence spectra are measured at 4, 20, 40, 80, 120, and 200 K, respectively. The recombination transition ...A series of GaAs/A1As multiple-quantum wells doped with Be is grown by molecular beam epitaxy. The photolu- minescence spectra are measured at 4, 20, 40, 80, 120, and 200 K, respectively. The recombination transition emission of heavy-hole and light-hole free excitons is clearly observed and the transition energies are measured with different quantum well widths. In addition, a theoretical model of excitonic states in the quantum wells is used, in which the symmetry of the component of the exciton wave function representing the relative motion is allowed to vary between the two- and three- dimensional limits. Then, within the effective mass and envelope function approximation, the recombination transition energies of the heavy- and light-hole excitons in GaAs/A1As multiple-quantum wells are calculated each as a function of quantum well width by the shooting method and variational principle with two variational parameters. The results show that the excitons are neither 2D nor 3D like, but are in between in character and that the theoretical calculation is in good agreement with the experimental results.展开更多
The resonant excitation is used to generate photo-excited carriers in quantum wells to observe the process of the carriers transportation by comparing the photoluminescence results between quantum wells with and witho...The resonant excitation is used to generate photo-excited carriers in quantum wells to observe the process of the carriers transportation by comparing the photoluminescence results between quantum wells with and without a p-n junction. It is observed directly in experiment that most of the photo-excited carriers in quantum wells with a p-n junction escape from quantum wells and form photoeurrent rather than relax to the ground state of the quantum wells. The photo absorption coei^cient of multiple quantum wells is also enhanced by a p-n junction. The results pave a novel way for solar cells and photodetectors making use of low-dimensional structure.展开更多
The carrier-density-dependent spin relaxation dynamics for modulation-doped GaAs/Al0.3 Gao,TAs quantum wells is studied using the time-resolved magneto-Kerr rotation measurements. The electron spin relaxation time and...The carrier-density-dependent spin relaxation dynamics for modulation-doped GaAs/Al0.3 Gao,TAs quantum wells is studied using the time-resolved magneto-Kerr rotation measurements. The electron spin relaxation time and its in-plane anisotropy are studied as a function of the optically injected electron density, Moreover, the relative strength of the Rashba and the Dresselhaus spin-rbit coupling fields, and thus the observed spin relaxation time anisotropy, is further tuned by the additional excitation of a 532nm continuous wave laser, demonstrating an effective spin relaxation manipulation via an optical gating method.展开更多
Material growth and device fabrication of the first 1.3μm quantum well （QW） edge emitting laser diodes in China are reported. Through the optimization of the molecular beam epitaxy （MBE） growth conditions and the...Material growth and device fabrication of the first 1.3μm quantum well （QW） edge emitting laser diodes in China are reported. Through the optimization of the molecular beam epitaxy （MBE） growth conditions and the tuning of the indium and nitrogen composition of the GalnNAs QWs, the emission wavelengths of the QWs can be tuned to 1.3μm. Ridge geometry waveguide laser diodes are fabricated. The lasing wavelength is 1.3μm under continuous current injection at room temperature with threshold current of 1kA/cm^2 for the laser diode structures with the cleaved facet mirrors. The output light power over 30mW is obtained.展开更多
AlGaAs/GaAs multi-quantum well (MQW) was prepared by molecular beam epitaxy(MBE) with growth-interrupted heterointerface (GIH) method and continuous growth (CG) method, respectively. The microstructures of the MQWs we...AlGaAs/GaAs multi-quantum well (MQW) was prepared by molecular beam epitaxy(MBE) with growth-interrupted heterointerface (GIH) method and continuous growth (CG) method, respectively. The microstructures of the MQWs were characterized by double-crystal X-ray rocking curve (DCRC) and atomic force microscopy (AFM), and the photoluminescence (PL) properties of the MQWs were also studied. The MQWs grown with GIH method show that higher order satellite peaks of Pendell?sung fringes are observed in DCRC, the roughness of surface is much reduced in AFM, and the full width at half maximum (FWHM) of exciton line is much narrower in PL. The results indicate that the GIH method reduces the monolayer growth step density at the heterointerface due to the migration of surface atoms for a few minutes growth interruption, and substantially improves the quality of AlGaAs/GaAs MQWs.展开更多
提出一种新型 Ga As/ Ga Al As子带间光吸收的红外光电导探测机理 ,利用 MOCVD系统进行器件材料的生长 ,研制了 2 0 0μm× 2 0 0μm的台面形式单管 ,测到了明显的红外光电流信号及阱间共振遂穿效应造成的负阻震荡现象 ,对器件的性...提出一种新型 Ga As/ Ga Al As子带间光吸收的红外光电导探测机理 ,利用 MOCVD系统进行器件材料的生长 ,研制了 2 0 0μm× 2 0 0μm的台面形式单管 ,测到了明显的红外光电流信号及阱间共振遂穿效应造成的负阻震荡现象 ,对器件的性能测试结果表明 ,器件的光电流响应和信噪比随着阱数增加而增加 ,器件噪声比常规 Ga As/ Ga Al展开更多
Strained InGaAs/GaAs quantum well (QW) was grown by low-pressuremetallorganic chemical vapor deposition (MOCVD). Growth interruption and strain buffer layer wereintroduced to improve the photoluminescence (PL) perform...Strained InGaAs/GaAs quantum well (QW) was grown by low-pressuremetallorganic chemical vapor deposition (MOCVD). Growth interruption and strain buffer layer wereintroduced to improve the photoluminescence (PL) performance of the InGaAs/GaAs quantum well. GoodPL results were obtained under condition of growth an interruption of 10 s combined with a moderatestrain buffer layer. Wavelength lasers of 1064 nm using the QW were grown and processed intodevices. Broad area lasers (100 μm x 500 μm) show very low threshold current densities (43 A/cm^2)and high slop efficiency (0.34 W/A, per facet).展开更多
This paper presents Atmospheric Pressure Metalorganic Chemical Vapor Deposition(AP-MOCVD) growth of GaAs/Al-xGa_(1-x)As multiquantum wells for the study of intersubband transition.The multiple quantum well structures ...This paper presents Atmospheric Pressure Metalorganic Chemical Vapor Deposition(AP-MOCVD) growth of GaAs/Al-xGa_(1-x)As multiquantum wells for the study of intersubband transition.The multiple quantum well structures are characterized by using cross-sectional transmission electron microscopy(TEM) and low temperature photoluminescence(PL),which are in consistent with the designed parameters.The in- frared absorption from intersubband transitions between the bounded- ground state and the extended excited state in GaAs/AtGaAs quantum wells shows peak at 10 μm with FWHM 250 cm^(-1).The absorption peak positions are in agreement with the calculated results based on the envelope function approximation.展开更多
We report a far-infrared absorption study of internal transitions of shallow Be acceptors in both bulk GaAs and a series of δ-doped GaAs/AlAs multiple quantum well samples with well thicknesses of 20,15 and 10 nm. Lo...We report a far-infrared absorption study of internal transitions of shallow Be acceptors in both bulk GaAs and a series of δ-doped GaAs/AlAs multiple quantum well samples with well thicknesses of 20,15 and 10 nm. Low temperature far-infrared absorp-tion measurements clearly show three principal absorption lines due to transitions of Be-acceptor states from the ground state to the first three odd-parity excited states,respec-tively. Using a variational principle,the 2p-1s transition energies of quantum confined Be acceptors are calculated as a function of the well width. It is found that the theoretical calculation of the 2pz → 1s transitions is in good agreement with the D-like line experi-mental data.展开更多
基金Project supported by Shandong Province Natural Science Foundation,China(Grant No.ZR2017MF018)the National Natural Science Foundation of China(Grant No.61675223)
文摘Three samples of GaAs/A1As multiple-quantum wells with different quantum well widths and tS-doped with Be ac- ceptors at the well center were grown on （100） GaAs substrates by molecular beam epitaxy. Polarized Raman spectra were recorded on the three samples at temperatures in a range of 4-50 K in a backscattering configuration. The two branches of coupled modes due to the interaction of the hole intersubband transitions and the quantum-well longitudinal optical （LO） phonon were observed clearly. The evaluation formalism of the Green function was employed and each lineshape of the Raman spectrum of the coupled modes was simulated. The dependence of the peak position of Raman shifts of the two coupled modes as well as the quantum-well LO phonon on the quantum-well size and measured temperature were given, and the coupling interaction mechanism between the hole subband transitions and the quantum-well LO phonon was researched.
基金supported by the National Natural Science Foundation of China(Grant No.61178039)the Natural Science Foundation of Shandong ProvinceChina(Grant No.ZR2012FM028)
文摘A series of GaAs/A1As multiple-quantum wells doped with Be is grown by molecular beam epitaxy. The photolu- minescence spectra are measured at 4, 20, 40, 80, 120, and 200 K, respectively. The recombination transition emission of heavy-hole and light-hole free excitons is clearly observed and the transition energies are measured with different quantum well widths. In addition, a theoretical model of excitonic states in the quantum wells is used, in which the symmetry of the component of the exciton wave function representing the relative motion is allowed to vary between the two- and three- dimensional limits. Then, within the effective mass and envelope function approximation, the recombination transition energies of the heavy- and light-hole excitons in GaAs/A1As multiple-quantum wells are calculated each as a function of quantum well width by the shooting method and variational principle with two variational parameters. The results show that the excitons are neither 2D nor 3D like, but are in between in character and that the theoretical calculation is in good agreement with the experimental results.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11574362,61210014,and 11374340the Innovative Clean-Energy Research and Application Program of Beijing Municipal Science and Technology Commission under Grant No Z151100003515001
文摘The resonant excitation is used to generate photo-excited carriers in quantum wells to observe the process of the carriers transportation by comparing the photoluminescence results between quantum wells with and without a p-n junction. It is observed directly in experiment that most of the photo-excited carriers in quantum wells with a p-n junction escape from quantum wells and form photoeurrent rather than relax to the ground state of the quantum wells. The photo absorption coei^cient of multiple quantum wells is also enhanced by a p-n junction. The results pave a novel way for solar cells and photodetectors making use of low-dimensional structure.
基金Supported by the National Natural Science Foundation Program of China under Grant Nos 11274302,11474276 and 61290303
文摘The carrier-density-dependent spin relaxation dynamics for modulation-doped GaAs/Al0.3 Gao,TAs quantum wells is studied using the time-resolved magneto-Kerr rotation measurements. The electron spin relaxation time and its in-plane anisotropy are studied as a function of the optically injected electron density, Moreover, the relative strength of the Rashba and the Dresselhaus spin-rbit coupling fields, and thus the observed spin relaxation time anisotropy, is further tuned by the additional excitation of a 532nm continuous wave laser, demonstrating an effective spin relaxation manipulation via an optical gating method.
文摘Material growth and device fabrication of the first 1.3μm quantum well （QW） edge emitting laser diodes in China are reported. Through the optimization of the molecular beam epitaxy （MBE） growth conditions and the tuning of the indium and nitrogen composition of the GalnNAs QWs, the emission wavelengths of the QWs can be tuned to 1.3μm. Ridge geometry waveguide laser diodes are fabricated. The lasing wavelength is 1.3μm under continuous current injection at room temperature with threshold current of 1kA/cm^2 for the laser diode structures with the cleaved facet mirrors. The output light power over 30mW is obtained.
文摘AlGaAs/GaAs multi-quantum well (MQW) was prepared by molecular beam epitaxy(MBE) with growth-interrupted heterointerface (GIH) method and continuous growth (CG) method, respectively. The microstructures of the MQWs were characterized by double-crystal X-ray rocking curve (DCRC) and atomic force microscopy (AFM), and the photoluminescence (PL) properties of the MQWs were also studied. The MQWs grown with GIH method show that higher order satellite peaks of Pendell?sung fringes are observed in DCRC, the roughness of surface is much reduced in AFM, and the full width at half maximum (FWHM) of exciton line is much narrower in PL. The results indicate that the GIH method reduces the monolayer growth step density at the heterointerface due to the migration of surface atoms for a few minutes growth interruption, and substantially improves the quality of AlGaAs/GaAs MQWs.
文摘提出一种新型 Ga As/ Ga Al As子带间光吸收的红外光电导探测机理 ,利用 MOCVD系统进行器件材料的生长 ,研制了 2 0 0μm× 2 0 0μm的台面形式单管 ,测到了明显的红外光电流信号及阱间共振遂穿效应造成的负阻震荡现象 ,对器件的性能测试结果表明 ,器件的光电流响应和信噪比随着阱数增加而增加 ,器件噪声比常规 Ga As/ Ga Al
文摘Strained InGaAs/GaAs quantum well (QW) was grown by low-pressuremetallorganic chemical vapor deposition (MOCVD). Growth interruption and strain buffer layer wereintroduced to improve the photoluminescence (PL) performance of the InGaAs/GaAs quantum well. GoodPL results were obtained under condition of growth an interruption of 10 s combined with a moderatestrain buffer layer. Wavelength lasers of 1064 nm using the QW were grown and processed intodevices. Broad area lasers (100 μm x 500 μm) show very low threshold current densities (43 A/cm^2)and high slop efficiency (0.34 W/A, per facet).
基金Work supported by the National Natural Science Foundation of China.
文摘This paper presents Atmospheric Pressure Metalorganic Chemical Vapor Deposition(AP-MOCVD) growth of GaAs/Al-xGa_(1-x)As multiquantum wells for the study of intersubband transition.The multiple quantum well structures are characterized by using cross-sectional transmission electron microscopy(TEM) and low temperature photoluminescence(PL),which are in consistent with the designed parameters.The in- frared absorption from intersubband transitions between the bounded- ground state and the extended excited state in GaAs/AtGaAs quantum wells shows peak at 10 μm with FWHM 250 cm^(-1).The absorption peak positions are in agreement with the calculated results based on the envelope function approximation.
文摘We report a far-infrared absorption study of internal transitions of shallow Be acceptors in both bulk GaAs and a series of δ-doped GaAs/AlAs multiple quantum well samples with well thicknesses of 20,15 and 10 nm. Low temperature far-infrared absorp-tion measurements clearly show three principal absorption lines due to transitions of Be-acceptor states from the ground state to the first three odd-parity excited states,respec-tively. Using a variational principle,the 2p-1s transition energies of quantum confined Be acceptors are calculated as a function of the well width. It is found that the theoretical calculation of the 2pz → 1s transitions is in good agreement with the D-like line experi-mental data.
