EPITAXIAL LATERAL OVERGROWTH OF INGAAS ON PATTERNED GAAS SUBSTRATES BY LIQUID-PHASE EPITAXY

InxGa1-xAs (x = 0.06) layers were grown on patterned ((111) over bar) GaAs substrates by liquid phase epitaxy. Two kinds of substrate struct ures were fabricated by using a GaAs wafer covered with a Si-x film. T he first type was a substrate which had only regular windows of 1 mm i n diameter in the SiNx film, and the second had trenches of 40-50 mu m in depth in the SiNx windows. For trenchless substrates, InGaAs later ally extended on the SiNx, film, finally resulted in a hexagonal shape . The etch pit density reduced dramatically on the epitaxial lateral o vergrowth layer, but was extremely high on the substrate. For trench-t ype substrates, InGaAs layers grew laterally from the side wall of a t rench towards the inside, forming a star-like pattern composed of {111 }A and {111}B planes. Then, this pattern changed to a triangular shape surrounded by {111}B planes since the growth rate of {111}B planes wa s slower than that of {111}A planes. The InGaAs layer formed a bridge over the trench. As a result, the EPD was extremely low in both layers inside and outside except in the trench periphery. It was shown that the growth of high quality crystals was possible by using a trench-typ e substrate.