GaAsSb spacer effect in quasi-type-II InAs coupled-QDs for intraband absorption enhancement

Abstract

We designed an InAs coupled quantum-dot (QD) structure with a GaAsSb spacer to form an intermediate band (IB). The electron and hole states are calculated using the k center dot p method. The numerical results revealed the band alignment changes to be quasi-type-II with 16% Sb. The 1 nm AlAs layers around the QD and 1 nm GaAs layer help in broadening the intraband absorption spectrum from the far infrared region to infrared range. The coupling QD structure with an 8.5 nm GaAsSb spacer and 16% Sb concentration exhibits better photoelectric efficiency for intermediate band solar cell in the simulation, with a 3.3% enhancement of the same PIN structure with GaAs as the intrinsic region. Introducing a GaAsSb layer in the coupling QD structure will also release the maximum shear stress in QD, exhibiting a 3% release with 16% a GaAsSb spacer. (C) 2017 Optical Society of America