  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.
