Structural Characteristics of Epitaxial Low-Temperature Grown {InGaAs/InAlAs} Superlattices on InP(100) and InP(111)A Substrates

The structural characteristics of {InGaAs/InAlAs} superlattices, grown by molecular-beam epitaxy (MBE) at a temperature of 200°C on InP substrates with the crystallographic orientations (100) and (111)A, have been investigated. The superlattices consist of 100 periods of alternating In0.53Ga0.47As and In0.52Al0.48As layers with nominal thicknesses of 12 and 8 nm, respectively. The structural quality of the samples has been investigated by transmission electron microscopy (TEM). It is shown that the superlattice on the InP(100) substrate is single-crystal with high concentration of stacking faults, twins, and small-angle domains. The superlattice on the InP(111)A substrate is polycrystalline; however, the grown layers can be traced throughout almost the entire superlattice. A wave-like curvature of the layers grown on the InP(111)A substrate is much larger than that of the layers grown on the InP(100) substrate: the angular ranges of layer deviation from the horizontal growth plane reach ±30° and ±18°, respectively.