Buffer-Free GeSn with High Relaxation Degree Grown on Si(001) Substrate for Photodetection

Abstract

In this paper, buffer-free germanium-tin (GeSn) films on Si(001) grown by molecular beam epitaxy are characterized. GeSn layers show high thermal stability under complementary metal-oxide-semiconductor processing conditions. The experimental results demonstrate that Ge0.928Sn0.072 film retains high crystallinity with few misfit dislocations formed at a relaxation degree of 91.5% after post-thermal annealing at 600 °C. Moreover, numerical simulations demonstrate that the proposed photodetector can achieve a high responsivity of 0.102 A/W at 2 μm. This strategy can facilitate the fabrication of GeSn-based devices, which will contribute substantially to the development of group IV-based infrared optoelectronics.

Keywords

• Buffer-free GeSn
• high relaxation degree
• photodetection