THE IMPACT OF OFFCUT OF GALLIUM ANTIMONIDE SUBSTRATES ON THE COMPOSITION OF EPITAXIAL INDIUM ARSENIDE ANTIMONIDE LAYERS

IR detectors give an image of the fine variations in the temperature of the landscape and are widely used in civil and defense applications. III/V materials are among the most common materials for the production of these detectors. In the past years it has become increasingly important to grow ternary and quaternary materials for future IR detectors. In the conventional growth temperatures in MBE systems, the III’s sticking coefficient is constant and assumed to be 1. On the other hand, a competition exists between the group V atoms which is influenced by growth temperature, V’s flux ratios, V/III flux ratio and other growth parameters. An additional parameter affecting this competition is substrate crystallographic orientation. In this study we present an investigation of the composition of InAsSb grown on (100) GaSb substrates having different offcut angles. In order to avoid parameter variation between different growths all epi-layers were grown in a single run in a multiwafer MBE system. Photoluminescence and XRD measurements revealed that InAsSb composition differs from layer to layer, suggesting that the As / Sb incorporation is sensitive to the type and density of the atomic steps on the growth surface (as shown by AFM measurements).