Mid- and long-infrared emission properties of InxGa1−xAsySb1−y quaternary alloy with Type-II InAs/GaSb superlattice distribution

Abstract

In this work, an InxGa1−xAsySb1−y quaternary alloy with a vertical distribution of type-II InAs/GaSb superlattices is grown in the miscibility gap using a fractional monolayer alloy (FMA) process on a vicinal surface. X-ray diffraction patterns indicate that InxGa1−xAsySb1−y quaternary alloys with high In contents (up to 50%–65%) still maintain pure phases and good crystal quality. Transmission electron microscopy with energy-dispersive spectroscopy is used to confirm the constituent elements of the quaternary alloy. In addition, a significant strain distribution phenomenon parallel to the growth direction (ϵxx) can be observed in the quaternary alloy using strain maps and related strain profiles. The mean strain peak values are close to those of conventional planar superlattices, including InAs/GaSb and InAs/InAsSb. Photoluminescence measurements and k∙p model calculations show that the vertical type-II InAs/GaSb superlattice distribution may generate a unique bandgap in the quaternary alloy by manipulating the FMA process on the vicinal surface. The quaternary alloy components and vertically-distributed superlattice parameters can be regulated, and the quaternary alloy bandgap can cover the mid-to long-wavelength infrared regions. This work offers an effective route to solve the miscibility problem and use neoteric quaternary alloys with carrier emission from the unique bandgap for infrared optoelectronic devices.