Growth of (In,Ga)As/(Al,Ga)As quantum wells on GaAs(1 1 0) by MBE

The structural and optical properties of (In,Ga)As/(Al,Ga)As quantum wells grown on GaAs(1 1 0) by conventional molecular beam epitaxy as well as by migration-enhanced epitaxy are studied by low-temperature photoluminescence (PL), cathodoluminescence (CL), atomic force microscopy (AFM) and transmission electron microscopy (TEM). The quality of GaAs/(Al,Ga)As quantum wells (QWs) allows to detect spin transport mediated by surface acoustic waves over distances up to 65 μm with spin lifetimes of about 22 ns. For (In,Ga)As/GaAs QWs, the accumulated strain due to the increase of the In mole fractions or the well thicknesses degrades the structural perfection more dramatically in structures with (1 1 0)-orientation than in structures with (0 0 1)-orientation. The quality of (In,Ga)As wells is remarkably improved by migration-enhanced epitaxy.