Enhanced electroluminescence from Ge-on-Si by precise in-situ doping and post-annealing

We obtain strong room-temperature electroluminescence (EL) from a Ge epitaxially grown on a Si. The epitaxial Ge is in situ doped with Boron and Phosphorous by low-temperature growth, allowing for precisely controlled p-i-n structures. Also Phosphorus delta-doping is performed at the surface, resulting in low-resistivity Ohmic contacts. Vertical-type mesa-defined diodes are fabricated and an excellent rectifying property with an on/off ratio over 10 5 is obtained, leading to the strong EL. It is remarkable that the post-growth-annealing drastically enhances the EL intensity, indicating that the Ge-on-Si is a promising high-efficiency light source on the Si platform.