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 In 0.53 Ga 0.47 As and In 0.52 Al 0.48 As 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.