Surface morphology of chemical vapor deposition grown ge on ge substrates

Geometrically defined Ge structures, projecting out from Ge surfaces deposited by a GeH₄-He system on (100) Ge substrates, all oriented in the same direction and having a similar shape, are observed using scanning electron microscopy. They indicate the existence of an epitaxial layer-substrate relationship. Under the same growth conditions, but at short deposition periods, these projections are isolated, but as the growth time increases their lateral dimensions increase, the average distance between them decreases, and coalescence occurs. They are identified as local overgrowth, which yields a rough surface, and their origin is attributed to surface and deposition conditions. Morphometric measurements made by an image analyzer have shown the time dependence of these progressive changes.