Enhanced Light Emission of Germanium Light-Emitting-Diode on 150 mm Germanium-On-Insulator (GOI)

Germanium-on-insulator (GOI) has become a novel platform for Ge-based electronic and photonic applications. Discrete photonic devices such as waveguides, photodetectors, modulators, and optical pumping lasers have been successfully demonstrated on this platform. To realize electric injection emitting is highly desirable towards integrated photonics. In this work, we report for the first time the Ge p−i−n light-emitting-diodes (LEDs) on the GOI substrate. The high-quality Ge LED on a 150-mm diameter GOI substrate was fabricated via direct wafer bonding followed by ion implantations. As a tensile strain of 0.19% has been introduced during the GOI fabrication process resulting from thermal mismatch, the LED devices exhibit a dominant direct bandgap transition peak near 0.785 eV (~1,580nm) at room temperature. In sharp contrast to conventional III-V LEDs, we found that the electroluminescence/photoluminescence (EL/PL) spectra show enhanced intensities as raising the temperature from 300 to 450 K as a consequence of higher occupation of direct bandgap. The maximum enhancement in EL intensity is a factor of 140% near 1,635 nm due to the improved optical confinement offered by the bottom insulator layer. This work potentially broadens the GOI's functional variety for applications in near-infrared sensing, electronics, and photonics.