Ge1−xSnx alloys synthesized by ion implantation and pulsed laser melting

The tunable bandgap and the high carrier mobility of Ge1−xSnx alloys stimulate a large effort for bandgap and strain engineering for Ge based materials using silicon compatible technology. In this Letter, we present the fabrication of highly mismatched Ge1−xSnx alloys by ion implantation and pulsed laser melting with Sn concentration ranging from 0.5 at. % up to 1.5 at. %. According to the structural investigations, the formed Ge1−xSnx alloys are monocrystalline with high Sn-incorporation rate. The shrinkage of the bandgap of Ge1−xSnx alloys with increasing Sn content is proven by the red-shift of the E1 and E1 + Δ1 critical points in spectroscopic ellipsometry. Our investigation provides a chip technology compatible route to prepare high quality monocrystalline Ge1−xSnx alloys.