Silicon-compatible
short- and midwave infrared emitters are highly
sought after for on-chip monolithic integration of electronic and
photonic circuits to serve a myriad of applications in sensing and
communication. Commercially available infrared light-emitting diodes
(LEDs) are predominantly made of III–V materials, which are
costly and not silicon-compatible. These materials suffer a degraded
performance if the emitting wavelength is longer than 2.35 μm.
To address this long-standing challenge, GeSn semiconductors have
been proposed as versatile building blocks for silicon-integrated
optoelectronic devices. In this regard, this work demonstrates LEDs
consisting of a vertical PIN double heterostructure p-Ge0.94Sn0.06/i-Ge0.91Sn0.09/n-Ge0.95Sn0.05 grown epitaxially on a silicon wafer using a germanium
interlayer and multiple GeSn buffer layers. The emission from these
GeSn LEDs at variable diameters in the 40–120 μm range
is investigated under both DC and AC operation modes. The fabricated
LEDs exhibit room temperature emission in the extended short-wave
range centered around 2.5 μm under an injected current density
as low as 45 A/cm2. By comparing the photoluminescence
and electroluminescence signals, it is demonstrated that the LED emission
wavelength is not affected by the device fabrication process or heating
during the LED operation. Moreover, the measured optical power was
found to increase monotonically as the duty cycle increases, indicating
that the DC operation yields the highest achievable optical power.
The LED emission profile and bandwidth are also presented and discussed.