Temperature and Excitation Power Dependence of Bi-Excitonic Luminescence in InGaAs/GaAs Multiple Quantum Wells

摘要

A six period InGaAs/GaAs multiple quantum wells were grown with a fixed indium mole fraction of 0.1 during growth at different temperatures (480-600 °C) using MBE. Thus grown samples were studied using Fourier transform photolumine-scence spectroscopy. Five luminescence bands were observed at 1.404 eV, 1.411 eV, 1.440 eV, and 1.476 eV. The transitions at 1.440 eV and 1.476 eV found to have some dynamic behaviour with respect to the excitation intensity. Their relative intensities were observed as a function of excitation power and found to have linear dependence, while their associated transitions have almost constant behaviour. These transitions were related to excitonic and bi-excitonic molecules. The appearance of bi-excitons in only two quantum wells indicates the uniform distribution of indium and smooth interfaces in two quantum wells grown at relatively higher temperatures (>560 °C). From these results it was inferred that the alloy disorder and uneven interfaces could forbid the bi-excitonic transitions that indicate a perfect crystal growth.