A three-dimensional model of GaAs/A1GaAs quantum double rings in the lateral static electric field is investigated theoretically. The eigenvalue problem with the effective-mass approximation is solved by means of the ...A three-dimensional model of GaAs/A1GaAs quantum double rings in the lateral static electric field is investigated theoretically. The eigenvalue problem with the effective-mass approximation is solved by means of the finite-element method. The energy levels and wave functions of quantum-confined electrons and heavy holes are obtained and show an agreement with our previous theoretical and experimental studies. It is shown in the approximation of neglecting the Coulomb attraction between the electron and heavy hole that a relatively large Stark shift of exciton emission of 4 meV is attainable with an applied electric field of 0.7 kV/cm.展开更多
For enhancement-mode InGaP/A1GaAs/InGaAs PHEMTs,gate annealing is conducted between gate structures of Ti/Pt/Au and Pt/Ti/Pt/Au. Comparison is made after thermal annealing and an optimum annealing process is ob- taine...For enhancement-mode InGaP/A1GaAs/InGaAs PHEMTs,gate annealing is conducted between gate structures of Ti/Pt/Au and Pt/Ti/Pt/Au. Comparison is made after thermal annealing and an optimum annealing process is ob- tained. Using the structure of Ti/Pt/Au, about a 200mV positive shift of threshold voltage is achieved by thermal annea- ling at 320℃ for 40min in N2 ambient. Finally, a stable and consistent enhancement-mode PHEMT is produced successfully with higher threshold voltage.展开更多
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
We have theoretically studied the mobility limited by interface roughness scattering on two-dimensional electrons gas（2DEG） at a single heterointerface（triangle-shaped quantum well）.Our results indicate that,like ...We have theoretically studied the mobility limited by interface roughness scattering on two-dimensional electrons gas（2DEG） at a single heterointerface（triangle-shaped quantum well）.Our results indicate that,like the interface roughness scattering in a square quantum well,the roughness scattering at the Al_xGa_（1-x）As/GaAs heterointerface can be characterized by parameters of roughness height A and lateral A,and in addition by electric field F.A comparison of two mobilities limited by the interface roughness scattering between the present result and a square well in the same condition is given.展开更多
Lead poisoning is a serious environmental concern, which is a health threat. Existing technologies al- ways have some drawbacks, which restrict their application ranges, such as real time monitoring. To solve this pro...Lead poisoning is a serious environmental concern, which is a health threat. Existing technologies al- ways have some drawbacks, which restrict their application ranges, such as real time monitoring. To solve this problem, glutathione was functionalized on the Au-coated gate area of the pseudomorphic high electron mobility transistor （pHEMT） to detect trace amounts of Pb^2＋. The positive charge of lead ions will cause a positive potential on the Au gate of the pHEMT sensor, which will increase the current between the source and the drain. The response range for Pb^2＋ detection has been determined in the concentrations from 0.1 pmol/L to 10 pmol/L. To our knowledge, this is currently the best result for detecting lead ions.展开更多
基金supported by a Grant-in-Aid for Scientific Research from the Ministry of Education,Science,Sports,and Culture of Japan (No.20340080).
文摘A three-dimensional model of GaAs/A1GaAs quantum double rings in the lateral static electric field is investigated theoretically. The eigenvalue problem with the effective-mass approximation is solved by means of the finite-element method. The energy levels and wave functions of quantum-confined electrons and heavy holes are obtained and show an agreement with our previous theoretical and experimental studies. It is shown in the approximation of neglecting the Coulomb attraction between the electron and heavy hole that a relatively large Stark shift of exciton emission of 4 meV is attainable with an applied electric field of 0.7 kV/cm.
文摘For enhancement-mode InGaP/A1GaAs/InGaAs PHEMTs,gate annealing is conducted between gate structures of Ti/Pt/Au and Pt/Ti/Pt/Au. Comparison is made after thermal annealing and an optimum annealing process is ob- tained. Using the structure of Ti/Pt/Au, about a 200mV positive shift of threshold voltage is achieved by thermal annea- ling at 320℃ for 40min in N2 ambient. Finally, a stable and consistent enhancement-mode PHEMT is produced successfully with higher threshold voltage.
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.
文摘We have theoretically studied the mobility limited by interface roughness scattering on two-dimensional electrons gas（2DEG） at a single heterointerface（triangle-shaped quantum well）.Our results indicate that,like the interface roughness scattering in a square quantum well,the roughness scattering at the Al_xGa_（1-x）As/GaAs heterointerface can be characterized by parameters of roughness height A and lateral A,and in addition by electric field F.A comparison of two mobilities limited by the interface roughness scattering between the present result and a square well in the same condition is given.
基金Project supported by the National Natural Science Foundation of China(Nos.61204012,61274049,61376058)the Beijing Natural Science Foundation(Nos.4142053,4132070)the Beijing Nova Program(Nos.2010B056,xxhz201503)
文摘Lead poisoning is a serious environmental concern, which is a health threat. Existing technologies al- ways have some drawbacks, which restrict their application ranges, such as real time monitoring. To solve this problem, glutathione was functionalized on the Au-coated gate area of the pseudomorphic high electron mobility transistor （pHEMT） to detect trace amounts of Pb^2＋. The positive charge of lead ions will cause a positive potential on the Au gate of the pHEMT sensor, which will increase the current between the source and the drain. The response range for Pb^2＋ detection has been determined in the concentrations from 0.1 pmol/L to 10 pmol/L. To our knowledge, this is currently the best result for detecting lead ions.
