Growth of lattice matched InAs/AlSb superlattices by molecular beam epitaxy

Abstract

The InAs/GaSb superlattices (SPLs) is an important component of quantum cascade laser (QCL) and interband cascade laser (ICL). In particular, the upper and lower SPL waveguide layers of the ICL are alternately grown from a large number of ultra-film epitaxial layers (nm) by molecular beam epitaxy(MBE). Subtle lattice mismatch may directly lead to the deterioration of material crystal quality, and the change of thicknessand the composition of each layer will strongly affect the structural performance of device material. The optimal growth temperature of InAs/GaSb SPLs is about 420 ℃. By growing GaSb/AlSb and InAs/GaSb SPL both with 40 short periods under the substrate rotating, the thickness of GaSb layer and AlSb layer are 5.448 nm and 3.921 nm, and the thickness of InAs layer and GaSb layer are 8.998 nm and 13.77 nm, respectively. The error is within about 10%, and the optimal growth conditions of InAs/AlSb SPLs are obtained. A lattice matched 40-period InAs/AlSb superlattice waveguide layer is grown on GaSb substrate. The influence of drifting As injection on the average lattice constant of InAs/AlSb superlattice is fully considered. Under the condition of fixed SOAK time of 3 s, the As pressure is changed to 1.7 × 10<sup>–6</sup> mbar to adjust the average lattice constants of the superlattices and achieve their matching with the GaSb substrate lattice. The experimental results show that the 0 order satellite peak of the SPL coincides with the peak of the GaSb substrate, and has a perfect lattice matching, and that the sharp second order satellite peak and the periodic structure good repeatability also indicate that the superlattice material has the excellent structural quality of the SPLs structure.