Room-Temperature Electroluminescence From GeSn Light-Emitting Pin Diodes on Si

In this letter, a GeSn light-emitting pin diode integrated on Si via a Ge buffer is demonstrated and it is compared with a light-emitting pin diode made from pure, unstrained Ge on Si. The diode layer structures are grown with a special low-temperature molecular beam epitaxy process. The pseudomorphic GeSn layers (1.1% Sn content) on the Ge buffer are compressively strained. Both light-emitting pin diodes clearly show direct bandgap electroluminescence emission at room temperature. The electroluminescence peak of the GeSn light-emitting pin diode is shifted by 20 meV into the infrared region compared to the electroluminescence peak of the unstrained Ge light-emitting pin diode. The shift is due to the lower bandgap of GeSn and the influence of strain.