A Study of Semiconductor Quantum Structures by Microwave Modulated Photolumenescence

Abstract

Abstract. Mixed types I-type II multiple quantum wells structures consist of alternating narrowand wide GaAs wells (WW and NW), separated by AlAs barriers. Transfer of electrons from the narrow-to the wide well results in the formation of two-dimensional electron and hole gases (2DEG and 2DHG) at the WW and NW, respectively. The present study investigated the influence of the 2DEG and the 2DHG on the optical properties of the materials. The study utilized two modulations techniques: double beam photoluminescence and microwave modulated PL, offering high-resolution spectroscopy, control of the density of the gases and their kinetic energy. The results showed that the existence of the low density 2DEG in the wide well cause the formation of trions or plasma-like recombination. In addition, electrons transfer through the barrier leads to a barrier-NW indirect recombination emission. The latter is influenced by an electrostatic potential induced by the two-dimensional gases.