GaAs／AlGaAs窄量子阱中激子二维特性的退化

DEGENERATION OF QUASI-TWO-DIMENSIONAL PROPERTIES OF EXCITONS IN NARROW GaAs/AIGaAs QUANTUM WELLS

用光荧光（ＰＬ）和时间分辨光谱（ＴＲＰＬ）技术研究了ＧａＡＳ／ＡＩＧａＡＳ量子阱结构中荧光上升时间τｆ和激子谱线半宽（ＦＷＨＭ）随阱宽的变化关系，发现在窄阱中，τｆ，随阱宽的变化关系与宽阱时的情况恰恰相反，在窄阱中τｆ随着阱宽的减小而增加，归结为激子二维特性的退化导致声学声子对激子的散射作用减弱造成的．同时观测到窄阱中谱线半宽随着阱宽减小而增加，这也是因为激子特性由维二维向三维转化造成的．

By using photoluminescence(PL)and time-resolved photoluminescence(TRPL),the well-width dependence of luminescence rising-time τf and the exciton FWHM in very narrow GaAs/AlGaAs quantum wells was investigated.It was found that τf increases with decreasing well-width. This is attributed to the reduction of acoustic phononexciton scattering rate,caused by the degeneration of quasi-two-dimensional properties of exctitons in narrow wells.The increase of exciton FWHM with decreasing well-width in narrow wells due to the transition from the quasi-two-dimensional to three-dimensional nature of the excitons was also observed.