Enhancement of photoluminescence from n-type tensile-strained GeSn wires on an insulator fabricated by lateral liquid-phase epitaxy

Abstract

We investigated the optical properties of undoped and n-type GeSn wires fabricated by a lateral liquid-phase epitaxial method. The Sn concentration was approximately 0.5% in the region from the seed to near the wire end. Moreover, the Sn concentration increased to 6% at the wire end, whereas Si diffusion from the seed was enhanced and extended to 200 μm from the seed. Tensile strain gradually decreased from 0.5% close the seed to 0.25% at the wire end. The photoluminescence (PL) peak was red-shifted by Sn incorporation into the Ge wires, and a PL peak at 0.66 eV was observed from the wire end. Upon n-type doping, the PL intensity of the GeSn layers was significantly enhanced to approximately 10 times higher than that of the undoped GeSn wires.