Influence of stress and surface reconstruction on the morphology of tensile GaInAs grown on InP(001) by gas source molecular beam epitaxy

Abstract

Tensile/compressive and tensile/lattice matched Ga 1 − x In x As multilayers have been grown by gas source molecular beam epitaxy (GS-MBE) on InP(001) and examined by transmission electron microscopy (TEM). The tensile layers exhibit undulations parallel to [1 1 0] for a lattice mismatch of −0.5% and prismatic mesas for lattice mismatches of −1 and −1.7%. The facets making up the mesas are mainly of the (114)A and (113)A types. These growth modes are accounted for by elastic relaxation mechanisms. The relationship between the various morphologies and lattice mismatch is discussed by reviewing the competition between elastic energy and surface energy. It is shown that the relaxation can be partially or fully frozen by decreasing the growth temperature or increasing the V/III flux ratio. The dependence upon the growth technique is also underlined by comparison with metalorganic vapor phase epitaxy (MOVPE). The modulation anisotropy and the frequent occurrence of (114)A facets are examined in terms of surface reconstruction. It is suggested that the crystallographic morphology of (114)A facets facilitates a reconstruction which is very similar to the regular 2 × 4 reconstruction of the (001) GaAsAs surface. Therefore the exact nature of steps and facets and their surface reconstruction should be taken into account in elastic relaxation mechanisms.