GeSi Heterostructures by Crystallization of Amorphous Layers

Heterostructure of GexSi100−x layers on Si〈100〉 substrates were fabricated by solid phase growth. The samples were analyzed by X-ray diffraction, transmission electron microscopy, megaelectronvolt backscattering spectrometry and four-point probe measurements before and after thermal annealing. The conditions at the interface between the amorphous layer and the substrate play an important role in controlling the crystalline structure of the grown layer. With increasing content of germanium in the alloy, the onset time (delay time) for crystallization is observed to decrease. A model is developed to rationalize the crystallization behavior observed on both single-crystal silicon and SiO2 substrates.