Extended-SWIR GeSn LEDs with Reduced Footprint and Efficient Operation Power

Abstract

Complementary metal oxide semiconductor-compatible short- and midwave infrared emitters are highly coveted for the monolithic integration of silicon-based photonic and electronic integrated circuits to serve a myriad of applications in sensing and communication. In this regard, the group IV germanium–tin (GeSn) material epitaxially grown on silicon (Si) emerges as a promising platform to implement tunable infrared light emitters. Indeed, upon increasing the Sn content, the bandgap of GeSn narrows and becomes direct, making this material system suitable for developing an efficient silicon-compatible emitter. With this perspective, microbridge PIN GeSn LEDs with a small footprint of 1520 μm2 are demonstrated, and their operation performance is investigated. The spectral analysis of the electroluminescence emission exhibits a peak at 2.31 μm, and it red-shifts slightly as the driving current increases. It is found that the microbridge LED operates at a dissipated power as low as 10.8 W at room temperature and just 3 W at 80 K. This demonstrated low operation power is comparable to that reported for LEDs having a significantly larger footprint reaching 106 μm2. The efficient thermal dissipation of the current design helped reduce the heat-induced optical losses, thus enhancing light emission. Further performance improvements are envisioned through thermal and optical simulations of the microbridge design. These simulations indicate that the use of GeSn-on-insulator substrate for developing a similar microbridge device is expected to improve the optical confinement toward the realization of electrically driven GeSn lasers.