Mid-Infrared GeSn-Based LEDs with Sn Content up to 16%

We have grown by Reduced Pressure Chemical Vapor Deposition (RPCVD) vertical GeSn light-emitting diodes (LEDs) with (i) Sn content ranging from 6% to 16% and (ii) with or without SiGeSn barriers. Direct band-gap behaviors and activation energies of defects affecting emission efficiency of our different stacks were analyzed by temperature dependent electroluminescence measurements. A strong light emission enhancement was observed thanks to SiGeSn confinement barriers compared to reference samples. The electroluminescence intensity of Ge0.84Sn0.16 LEDs was increased by a factor 2 compared to that of Ge0.87Sn0.13 devices. This strong enhancement at room temperature is attributed to the increase of the splitting energy between Γ and L valleys for higher Sn content LEDs.