Thickness dependent solid-phase crystallization of amorphous GeSn on insulating substrates at low temperatures (≤250°C)

Low-temperature (≤250°C) solid-phase crystallization of amorphous-GeSn films (Sn-concentration: 20%-30%, thickness: 30-100 nm) on insulating-substrates are investigated. As a result, we have realized high growth-rate (∼13 μm/h) for samples (film-thickness: 100 nm, initial Sn-concentration: 30%) at surprisingly low-temperature (150°C), which is very useful to realize flexible thin-film transistors. During this study, we encountered interesting phenomena that growth rates significantly decrease with decreasing filmthickness. In addition, substitutional Sn-concentrations in grown layers increased with decreasing film thickness. These phenomena are attributed to change in bond arrangement processes caused by interface. This technique is expected to facilitate next generation flexible thin-film transistors.