Electronic structure and optical gain of InAsSbN/InAs quantum dots

Abstract

The electronic structure and optical gain of InAsSbN/InAs QDs are investigated in the framework of effective-mass envelope function theory. The strain distribution is calculated using the valence force field (VFF) method. When the composition of Sb increases, both the conduction and valence bands offset and the compressive strain increase, and the transition energy decreases and the strained band alignment may change from type I to type II. The added nitrogen can reduce the compressive strain in QD, and it reduces the C1-HH1 transition energy due to the strong repulsion between nitrogen resonant band and conduction band. When the Sb composition increases, the overlapping of wave-functions of electrons and holes are less efficient, the optical transition matrix element decreases. For the optical gain, we should consider the factors including the transition matrix element, the matrix element of Kane’s theory, the refractive index and Fermi-Dirac distributions for electrons f c in the conduction bands and holes f v in the valence bands. So depending on the specific application requirements, we should select the appropriate compositions of Sb and N accordingly.