GeSn Nanobeam Light-Emitting Diode as a GHz-Modulated Light Source

Designs and theoretical analysis are presented for a room temperature resonant-cavity-enhanced GeSn LED whose emission peaks at the 2
$\mu$
m wavelength. The Ge/GeSn/Ge PIN hetero-diode of length 1
$\mu$
m is embedded in a rib-type Ge-on-Si nanobeam having either 24 or 36 air holes. The maximum LED modulation bandwidth
$f_{3\text{dB}}$
is proportional to the Purcell factor and is inversely proportional to
$\tau _{s\,p0}$
the GeSn bulk spontaneous emission lifetime. For an emission linewidth of 200 nm and
$\tau _{s\,p0}$
of 10 ns, an
$f_{3\text{dB}}$
of 1.6 GHz is predicted.