A Study on The Optical Properties of Long-Infrared Intraband Transitions of Quadruple Gaas/Alxga1-Xas Quantum Well Under Applied Electric Field

Abstract

Semiconductor-emitting/absorbing infrared devices are in the common interest of the scientific and industrial community due to their broad application in these fields. GaAs/AlGaAs based devices are one of the most studied semiconductor heterostructures. In this study, I have aimed to design GaAs/AlGaAs quantum well (QW) semiconductor heterostructures to emit/absorb in the long infrared region and studied the optical properties. To do that, I have designed a quadruple QW, which is composed of GaAs/Al0.44Ga0.56As QW and quantum barriers (QB). I have solved the time-independent Schrödinger equation using the finite element method-based matlab code under effective mass approximation. The wave functions and corresponding energy eigenvalues are obtained for varied electric field (EF) intensities. I have shown that our design can operate up to 80 kV/cm, which is the limit for first bounded energy eigenstates. It is observed that E_32 transition provides long-infrared emission/absorption corresponding to the 0.12-0.14 eV transition energy and it is constant with increased EF intensity. In addition, it is seen that the overlap of the wave functions is increasing with EF intensity which enhances radiative transition in the structure. I have calculated the linear absorption coefficient and refractive index change. I have observed that the absorption coefficient of E_32 transition is increasing with EF intensity while E_31 is decreasing and E_21 is constant. As a last, I have shown that EF intensity has a minor effect on refractive index change.