Exciton dynamics in GaAs/GaAlAs InGaAs/GaAs and InGaAs/AlGaAs quantum wells

摘要

Abstract: Photoluminescence (PL) and time-resolved PL measurements were used to study the exciton recombination processes in GaAs/AlGaAs, InGaAs/GaAs, and InGaAs/AlGaAs quantum wells (QWs). An increasing lifetime with decreasing well width has been observed in very narrow and high quality GaAs/AlGaAs samples, and attributed to the reduced overlap of the electron and hole wave functions and the increase of the exciton effective volume. In InGaAs/GaAs strained QWs the measured exciton lifetimes were found to be of In composition dependence: the more the indium composition, the shorter the lifetime. The mechanisms, including the random alloy disordering and the degeneration of quasi two-dimensional properties of excitons were inferred to explain the experimental results. The nonradiative recombination was stressed in our InGaAs/AlGaAs QWs. A combined analysis of cw PL and time-resolved PL measurements allows us to separate the radiative and nonradiative decay times in our sample. The observed dominant nonradiative recombination has been tentatively ascribed to the poor quality of AlGaAs. !