High Sn-Content GeSn Light Emitters for Silicon Photonics

The present chip technology is based on silicon with increasing number of other materials integrated into electrical circuits. This chapter presents a systematic photoluminescence (PL) study of compressively strained, direct-bandgap GeSn alloys, followed by the analysis of two different optical source designs. First, a direct bandgap GeSn light emitting diode (LED) will be characterized via power-and temperature-dependent electroluminescence (EL) measurements. Then, lasing will be demonstrated in a microdisk (MD) resonator under optical pumping. The integration of direct-bandgap GeSn-based devices as a light source for on-chip communications offers the possibility to monolithically integrate the complete photonic circuit within mainstream silicon technology. The chapter describes material properties using Ge0.875Sn0.125 epilayers of various thicknesses. Temperature-dependent integrated PL intensity is a suitable method to determine whether a semiconductor has a direct or indirect fundamental bandgap. In conclusion, the chapter presents growth and optical characterization of high-quality GeSn alloys with very high Sn content.