Large-grain Sn-doped Ge (100) on insulator by aluminum-induced crystallization at low-temperature for flexible electronics

A low-temperature formation technique of Sn-doped Ge on insulator has been investigated by aluminum-induced crystallization using a-GeSn/Al stacked structures. For a-GeSn films (Sn concentration: 2%), the layer-exchange growth temperature is significantly decreased compared with a-Ge, which enables low temperature growth at 250°C. At such a low temperature, bulk nucleation of GeSn in Al layers is significantly suppressed, and (100)-oriented interface nucleation becomes dominant. On the other hand, growth rate becomes high by Sn-doping effects. As a result, formation of (100)-oriented large-grain (>10 μm) Sn-doped Ge (Sn concentration: 2%) crystals on insulating substrates becomes possible at a low temperature (250°C). This technique will be useful to realize advanced flexible electronics.