[(AlN)1/(GaN)n1]m/(AlN)n2-based quantum wells for quantum-cascade-laser application

[(AlN)1/(GaN)n1]m/(AlN)n2-based quantum wells (QWs) constructed by periodically introducing several atomic layers of AlN into (AlN)1/(GaN)n1 short-period superlattices have a great potential for the application to mid-infrared quantum-cascade lasers. Effective electron injection from the first to second subbands in the (AlN)1/(GaN)n1 short-period superlattice is expected through the inserted (AlN)n2 layer which has a large polarization field. The [(AlN)1/(GaN)n1]m/(AlN)n2 QWs were prepared by hot wall epitaxy, and the structure was characterized by transmission electron microscopy and X-ray diffraction. The quality of [(AlN)1/(GaN)n1]m/(AlN)n2 QW depends significantly on the quality of GaN buffer layer, and high-quality QW structures were prepared on GaN films grown on Al2O3 (0001).