Continuous-wave GeSn light emitting diodes on silicon with $2.5 \, \mu$m room-temperature emission

TL;DR

This paper reports the development of silicon-compatible GeSn LEDs that emit at 2.5 μm at room temperature, demonstrating a significant step toward integrated infrared photonics for sensing and communication.

Contribution

The work introduces the first GeSn LEDs on silicon with room-temperature emission at 2.5 μm, using a novel epitaxial heterostructure and demonstrating their operational stability and scalability.

Findings

Room-temperature emission at 2.5 μm achieved

LED emission unaffected by fabrication and heating

Optical power increases with duty cycle

Abstract

Silicon-compatible short- and mid-wave 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. To address this longstanding challenge, GeSn semiconductors have been proposed as versatile building blocks for silicon-integrated optoelectronic devices. In this regard, this work demonstrates light-emitting diodes (LEDs) consisting of a vertical PIN double heterostructure p-Ge$_{0.94}$Sn$_{0.06}$/i-Ge$_{0.91}$Sn$_{0.09}$/n-Ge$_{0.95}$Sn$_{0.05}$ grown epitaxially on a silicon wafer using germanium interlayer and multiple GeSn buffer layers. The emission from these GeSn LEDs at variable diameters in the 40-120 $\mu$m range is investigated under both DC and AC operation modes. The fabricated LEDs exhibit a room temperature emission in the extended short-wave range centered around 2.5 $\mu$m under an injected current density as low as 45 A/cm$^2$. 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.