Degradation of Intersubband Transitions in Electron Irradiated GaAs/AlGaAs Multiple Quantum Wells With Superlattice Barriers

Abstract

AbstractIntersubband transitions in GaAs/AIGaAs multiple quantum wells (MQWs) are studied as a function of 2 MeV electron irradiation doses using the optical absorption technique. The MQW structure was designed with a 5 period Al.4Ga.6As/GaAs superlattice barrier, and two transitions are observed in the spectra. These transitions occur from the ground state to the first excited state and to the miniband formed by the superlattice barrier. The total integrated area from both transition spectra are studied as a function of temperature and electron irradiation dose. For the ground state to first excited state transition the total integrated area decreases exponentially as the irradiation dose increases, which could be explained in terms of the trapping of the 2D-electron gas in the quantum well by the irradiation induced defects. In comparison, the intensity of the ground state to miniband transition was found to increase exponentially as a function of the irradiation dose. Two possible explanations for this behavior are suggested. The temperature dependence of the integrated area of both transitions is also presented.