Low-temperature stress-assisted germanium-induced crystallization of silicon–germanium alloys on flexible polyethylene terephtalate substrates

The application of mechanical-compressive stress during low-temperature annealing has been investigated for the crystallization of SiGe alloys on plastic substrates. It was observed that crystallization of an amorphous Ge/Cu/Ge “sandwich” can occur at temperatures as low as 130 °C with the application of an equivalent compressive strain of 0.05%. By using this sandwich as a seed for crystallization of an underlying amorphous SiGe film, partial crystallization of the film was observed to occur at a temperature of 180 °C, again under an equivalent compressive strain of 0.05%. Without the application of the compressive strain, crystallization was not observed for either system at the temperatures investigated. The atomic percentage of Si in the SiGe alloy was 35% as confirmed by Rutherford backscattering spectroscopy and the partial crystallization of the SiGe layer was verified by scanning electron microscopy, x-ray diffraction, and transmission-electron microscopy analyses.