Growth of a GeSi thick alloy layer on a Si substrate by liquid phase epitaxy

Abstract

A novel technique termed the “yo-yo solute feeding method”, for the preparation of either a thick layer of a GeSi alloy or a GeSi substrate is described. In this method, a Sn-Ge-Si solution was “sandwiched” between two sheets of a Si(111) crystal to form a double crystal system, and the temperature was periodically modulated with an amplitude of 10 to 20° C within the temperature range of 910 to 980° C to produce what has been termed a “yo-yo” cycle. A Ge0.24Si0.76 alloy layer about 0.8 mm thick was successfully grown on the bottom surface of the upper silicon(111) crystal. When a third Si sheet crystal was inserted between the two Si crystals to form a triple crystal system, epitaxial growth occurred on the bottom surface of the middle crystal and this was accompanied by meltback on the top surface. The implication of this result is that it may be possible to transform the entire middle Si crystal into a GeSi alloy following the application of numerous “yo-yo” cycles.