Sn composition graded GeSn photodetectors on Si substrate with cutoff wavelength of 3.3 <i>μ</i>m for mid-infrared Si photonics
Mingming Li, Jun Zheng, Xiangquan Liu, Yupeng Zhu, Chaoqun Niu, Yaqing Pang, Zhi Liu, Yuhua Zuo, Buwen Cheng
Abstract
The Sn composition graded GeSn layer with Sn content increased from 11% to 14.3% was grown on a Si substrate by molecular beam epitaxy. The structural properties of the GeSn layer are investigated, and the film is gradually relaxed along the thickness, reaching approximately 71.6%. The GeSn p–i–n detectors were fabricated by using a complementary metal oxide semiconductor compatible process. The GeSn detectors demonstrated a cutoff wavelength of approximately 3.3 μm at room temperature with a dark current of 0.3 A/cm2 @ -1 V. At a wavelength of 2000 nm, the GeSn detectors had a responsivity of 110 mA/W and -3 dB bandwidth (f3 dB) about 3 GHz. These results suggest that high Sn content relax GeSn can be grown by MBE and paves the way toward the feasibility of mid-infrared GeSn photonics.