Linear and nonlinear optical absorption coefficient and electronic features of triple GaAlAs/GaAs and GaInAs/GaAs quantum wells depending on barrier widths

Abstract

In the present work, the effect of the barrier widths (BWs) on the linear and nonlinear optical absorption coefficient (OAC) and the electronic features of asymmetric triple Ga1-xAlxAs/GaAs (A structure) and Ga1-xInxAs/GaAs (B structure) quantum wells (QW) was investigated. The wave-functions and energy levels of asymmetric triple quantum wells (ATQW) consisting of inverse semi V-shaped, inverse semi parabolic and semi parabolic quantum well were analyzed by solving the Schrödinger equation, using the effective mass approach. As the electrons in the ground state are mostly located into the semi-parabolic quantum well, they are less affected by BWs. However, the electrons in the second and third states show a great change due to the increase in BW between them. Our results present that the potential height, the energy levels and the energy differences of A structure are always lower than of B structure. Also, the linear and nonlinear OACs depend on BWs. The absorption spectrum of the intersubband indicates blue or red shifts, as the energy interval changes with BWs. Therefore, the variation of these coefficients, which may be suitable for various optical modulators and infra-red optical device applications, can be smoothly achieved by replacing BWs.