Creation of Germanium Circular-polarized LED toward Optical Encrypted Communication

Toward realization of Germanium circular-polarized LED for optical encrypted communication, Ge(111) high quality films were grown on Si(111) substrates. By means of wafer transfer technique, Ge-on-Insulator (GOI) substrates were fabricated. By depositing surface passivation films, we obtained large light emission enhancements. Mesa vertical type Ge(111) pin LEDs were fabricated by using in-situ doping, and very strong room temperature EL was successfully obtained. A single crystal high quality ferromagnetic films were grown as electrodes of the LED and the strong EL emission was obtained from the side edge, opening a route to realization of circular polarized light emission.