Al-induced low-temperature crystallization of Si1 − xGex (0 < x < 1) by controlling layer exchange process

Low-temperature (< 450 °C) Al-induced crystallization (AIC) of a-Si1 − xGex (0 < x < 1) films on an insulator has been investigated using a-Si1 − xGex/Al/quartz stacked structures. It was found that the crystal growth features drastically depends on the Ge fraction. Change of the stacked structures to Al/poly-SiGe/quartz uniformly occurred by annealing for low Ge fractions (< 50%). However, the layer exchange and crystallization occurred locally and heterogeneously for high Ge fractions (> 50%). To realize uniform crystallization for high Ge fractions, effects of interfacial Al oxide layer thickness on layer exchange were investigated. By optimizing the oxide layer thickness, the layer exchange process could be controlled, and thus, homogeneous crystallization with large grain sizes (> 20 μm) was achieved for samples with the whole Ge fractions. These findings will be a powerful tool for realizing large poly-SiGe on insulating films for high-efficiency thin-film solar cells and system-in-displays.