Emission characteristics of self-assembled strained Ge_1−xSn_x islands for sources in the optical communication region

Self-assembled strained Ge_{1− x} Sn _x islands on Si (100) have been grown at a low temperature using molecular beam epitaxy. The in-built strain and fraction of Sn in the islands have been estimated using x-ray photoelectron spectroscopy and high resolution x-ray diffraction study of grown samples. No-phonon assisted transition in the optical communication wavelength range of 1.4–1.8 μ m has been observed in the Ge_{1− x} Sn _x island samples. The direct band gap transition intensity is found to increase with a growth in Sn concentration, with this increase in intensity sustained up to a temperature of 130 K in Ge_{1− x} Sn _x islands. The observed electroluminescence in p-i-n devices fabricated on Ge_{1− x} Sn _x island samples above a threshold bias of 4 V makes them attractive for future Si based optical devices. (paper)