Ultra-low threshold cw and pulsed lasing in tensile strained GeSn alloys

Abstract

GeSn alloys are the most promising semiconductors for light emitters entirely based on group IV elements. Alloys containing more than 8 at.% Sn have fundamental direct band-gaps, similar to conventional III-V semiconductors and thus can be employed for light emitting devices. Here, we report on GeSn microdisk lasers encapsulated with a SiNx stressor layer to produce tensile strain. A 300nm GeSn layer with 5.4 at.% Sn, which is an indirect band-gap semiconductor as-grown with a compressive strain of -0.32 %, is transformed via tensile strain engineering into a truly direct band-gap semiconductor. In this approach the low Sn concentration enables improved defect engineering and the tensile strain delivers a low density of states at the valence band edge, which is the light hole band. Continuous wave (cw) as well as pulsed lasing are observed at very low optical pump powers. Lasers with emission wavelength of 2.5 um have thresholds as low as 0.8kWcm^-2 for ns-pulsed excitation, and 1.1kWcm^-2 under cw excitation. These thresholds are more than two orders of magnitude lower than those previously reported for bulk GeSn lasers, approaching these values obtained for III-V lasers on Si. The present results demonstrate the feasabiliy and are the guideline for monolithically integrated Si-based laser sources on Si photonics platform.

References in corpus (3)

• Optically pumped GeSn micro-disks with 16 % Sn lasing at 3.1 um up to 180K
• Low-threshold optically pumped lasing in highly strained Ge nanowires
• Temperature-dependent photoluminescence characteristics of GeSn epitaxial layers

Cited by in corpus (17)

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• Study of SiGeSn/GeSn single quantum well towards high-performance all-group-IV optoelectronics
• Extended-SWIR Photodetection in All-Group IV Core/Shell Nanowires
• Recrystallization and Interdiffusion Processes in Laser-Annealed Strain-Relaxed Metastable Ge${}_{0.89}$Sn0${}_{.11}$
• Magneto-optical determination of the carrier lifetime in coherent Ge(1-x)Sn(x)/Ge heterostructures
• Single SiGe Quantum Dot Emission Deterministically Enhanced in a High-Q Photonic Crystal Resonator
• Combined Iodine- and Sulfur-based Treatments for an Effective Passivation of GeSn Surface
• Impact of stoichiometry and strain on Ge${}_{1-x}$Sn${}_x$ alloys from first principles calculations
• Localized State-Induced Enhanced Intrinsic Phonon-Free Optical Transition in Silicon Nanocrystals
• Investigation of Lasing in Highly Strained Germanium at the Crossover to Direct Band Gap
• Germanium-Based Mid-Infrared Photonics