Improving the short-wave infrared response of strained GeSn/Ge multiple quantum wells by rapid thermal annealing

In this work, the evolution of structural, optical and optoelectronic properties of coherently strained Ge0.883Sn0.117/Ge multiple quantum wells (MQWs) grown by molecular beam epitaxy under rapid thermal annealing (RTA) is systematically investigated. The MQW structure remains fully-strained state with RTA at 400? or below and disrupts at higher annealing temperatures due to Sn segregation and interdiffusion of Ge and Sn atoms. The GeSn well layers exhibit the strongest absorption in 2.0-2.4 mu m after annealing at 400 C and become transparent above 1.8 mu m after RTA at 600? or beyond due to serve Sn segregation. Owing to improved crystal quality after RTA at 400?, the dark current of the fabricated metal-semiconductor-metal photodetector is effectively lowered by more than two times. Additionally, the responsivities at 1.55 and 2.0 mu m are improved by 4.15 and 3.78 folds, respectively, compared to those of the as-grown sample. The results can be an insightful guidance for the development of high-performance short-wave infrared photonic devices based on Sn-containing group-IV low-dimensional structures.

Automated summary

In this work, the evolution of structural, optical, and optoelectronic properties of coherently strained Ge0.883Sn0.117/Ge multiple quantum wells (MQWs) grown by molecular beam epitaxy under rapid thermal annealing (RTA) is investigated. The MQW structure remains fully-strained state with RTA at 400°C or below and disrupts at higher annealing temperatures due to Sn segregation and interdiffusion of Ge and Sn atoms. The results provide guidance for the development of high-performance short-wave infrared photonic devices based on Sn-containing group-IV low-dimensional structures.