Theoretical simulation of optical absorption coefficients in heterostructure based on semi-parabolic-double quantum wells

Abstract

In this work, we have performed a numerical calculation to obtain the lowest three electron subband energy levels and their density of probabilities in a n-doped heterostructure constituted by double semi parabolic quantum wells separated by square quantum well and surrounded by two outer barriers. The numerical investigation is carried out within the framework of the parabolic single band and effective mass approximations. Firstly, we have solved self-consistently the coupled Schrödinger and Poisson equations and have determined the electronic wave functions and subband energy levels. After that we have deduced the different contributions of the optical absorptions between the lowest three electron subband energy levels. The energy variations and the occupancy ratios are also discussed to show their accordance with the behavior of the total optical absorption coefficient. Throughout this study, two cases of doping were treated. The first one is a doping in the outer barriers and the second one was a doping in the inner barriers. The doping consists of inserting 1 nm of silicon layer in the middle of the barriers. The responses of different total optical absorption coefficients, subband energy levels and confining potential by increasing the concentration of the delta-doped layers are demonstrated and the two behaviors (red and blue shifted) are discussed in detail.