GeSn with a high substitutional Sn concentration (>7%) is an attractive direct band gap material for high-efficiency photodevices that can be merged with large-scale integrated circuits (LSIs). To achieve GeSn with high Sn concentration, low-temperature solid-phase epitaxy using amorphous-GeSn (a-GeSn) (Sn concentration: 10%-36%)/crystal-Ge (c-Ge) stacked structureswas investigated. Solid-phase growth of GeSnwas enhanced as Sn concentrationwas increased, which enabled epitaxial growth at very lowtemperature (150-200 degrees C). Interestingly, concentrations of substitutional Sn increased with decreasing growth temperature. As a result, epitaxial growth of GeSn with substitutional Sn concentrations of similar to 8% was achieved by decreasing the growth temperature to 150 degrees C using a-GeSn (Sn concentration: 36%)/c-Ge stacked structures. This technique is expected to be useful to realize multi-function LSIs, where high-efficiency photodevices are integrated with transistors. (C) 2015 Elsevier B. V. All rights reserved.