物理学报2017，Vol.66Issue(4)：249-255,7.DOI:10.7498/aps.66.046802
掺杂对称性对(110)晶向生长GaAs/AlGaAs量子阱中电子自旋弛豫动力学的影响
Effect of doping symmetry on electron spin relaxation dynamics in (110) GaAs/AlGaAs quantum wells
摘要
Abstract
Considerable interest has been aroused in the study of the spin dynamics in semiconductors due to its potential applications in spintronics and quantum computation. In this paper, time-resolved circularly polarized pump-probe spectroscopy is used to study the carrier density dependences on the electron spin relaxation in approximately symmetrical and completely asymmetrical doping (110) GaAs/AlGaAs quantum wells. With the increase of the carrier density, the spin relaxation time first increases and then decrease obviously in both of the quantum wells, and the measured spin relaxation time of the approximately symmetrical doping quantum wells is always longer than that of the asymmetrical doping one. By analysis, we find that the spin relaxation is not dominated only by the Bir-Aronov-Pikus (BAP) mechanism in (110) GaAs quantum wells, that though the Dresselhaus spin-orbit coupling does not lead to any spin relaxation, the asymmetry of the doping position contributes to the asymmetry of potential energy structure, thus the built-in electric field which can induce the Rashba spin-orbit coupling to appear, and that the effective magnetic field induced by the Rashba spin-orbit coupling normal to the growth direction can lead to spin relaxation along the growth direction. Therefore, the D′yakonov-Perel′ (DP) mechanism plays an important role in asymmetrical doping (110) GaAs/AlGaAs quantum wells. In the approximately symmetrical and completely asymmetrical doping (110) GaAs/AlGaAs quantum wells, the DP mechanism dominates the spin relaxation at low carrier density, thus the spin relaxation time increases with carrier density increasing due to the strengthening of the electron-electron scattering and the decreasing of the momentum relaxation time. However, at high carrier density, BAP mechanism plays an important role, thus the spin relaxation time decreases obviously with carrier density increrasing, but the decay rates in both of the quantum wells are slower than that in the casethat only BAP mechanism dominates, because both the DP and BAP mechanism play an important role. The strength of the Rashba spin-orbit coupling depends on the symmetry of the quantum well. The DP mechanism in a completely asymmetrical doping quantum well is stronger than that in an approximately symmetrical doping quantum wells, thus the decay rate in a completely asymmetrical doping quantum wells is always slower than that in an approximately symmetrical doping quantum wells, and the spin relaxation time in a completely asymmetrical doping quantum wells is shorter than that in an approximately symmetrical doping quantum wells.关键词
圆偏振光饱和吸收光谱/电子自旋弛豫/掺杂对称性/GaAs/AlGaAs量子阱Key words
circularly polarized pump-probe spectroscopy/electron spin relaxation/doping symmetry/GaAs/AlGaAs quantum wells引用本文复制引用
滕利华,牟丽君..掺杂对称性对(110)晶向生长GaAs/AlGaAs量子阱中电子自旋弛豫动力学的影响[J].物理学报,2017,66(4):249-255,7.基金项目
Project supported by the National Natural Science Foundation of China (Grant Nos. 11504194, 11274189) and the Scientific Development Project of Qingdao, China (Grant No. 14-2-4-101-jch). 国家自然科学基金(批准号: 11504194, 11274189)和青岛市应用基础研究计划项目青年专项(批准号: 14-2-4-101-jch)资助的课题. （Grant Nos. 11504194, 11274189）
