Extended-SWIR GeSn LEDs with reduced footprint and power consumption

TL;DR

This paper presents miniaturized GeSn LEDs on silicon with low power consumption and efficient thermal management, advancing CMOS-compatible infrared emitters for integrated photonics.

Contribution

It demonstrates the first microbridge GeSn LEDs with a small footprint and low power operation, highlighting design strategies for improved thermal dissipation and potential laser development.

Findings

Peak emission at 2.31 μm with slight red-shift at higher currents

Operation power as low as 3 W at 80 K, 10.8 W at room temperature

Comparable or better performance than larger footprint LEDs

Abstract

CMOS-compatible short- and mid-wave 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 communications. In this regard, a 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 $1,520$ $\mu$m$^2$ are demonstrated and their operation performance is investigated. The spectral analysis of the electroluminescence emission exhibits a peak at $2.31$ $\mu$m 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 $10^6$ $\mu$m$^2$. The efficient thermal dissipation of the current design helped to reduce the heat-induced optical losses, thus enhancing light emission. Further performance improvements are envisioned through thermal and optical simulations of the microbridge design. The use of GeSnOI substrate for developing a similar device is expected to improve optical confinement for the realization of electrically driven GeSn lasers.