量子限制效应对δ掺杂GaAs/AlAs多量子阱中铍受主态寿命的影响

Effect of quantum confinement on acceptor state lifetime in Be δ doped GaAs/AlAs multiple quantum wells

采用远红外时间分辨光谱,研究了量子限制效应对δ掺杂在GaAs/AlAs多量子阱中铍(Be)受主态寿命的影响.在低温下的远红外吸收谱中,清楚地观察到了三条主要吸收线,它们分别来源于铍受主从基态到它的三个奇宇称激发态的跃迁.实验结果表明:随着量子限制效应的增强,受主激发态寿命而减少,实验测得体材料中Be受主2p激发态的寿命是350 ps,而阱宽10 nm的多量子阱中的寿命是55 ps.量子限制效应对布里渊区折叠声学声子模的影响增强了受主带内空穴与声学声子相互作用,从而加快了受主带内空穴的弛豫过程.

Using far-infrared time-resolved spectroscopy,we have investigated the effect of quantum-well confinement on the lifetime of shallow acceptor states in GaAs/AlAs multiple quantum wells with Be δ-doping.Low-temperature far-infrared absorption 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,respectively.It is found that the lifetime of excited states is monotonically reduced with decreasing quantum-well width,from 350 ps in bulk to 55 ps in a 100 well.We suggest that the effect of quantum-well confinement on zone-fold acoustic-phonon modes increases the intra-acceptor scattering rate of acoustic-phonon-assisted relaxation.