High-performance back-illuminated Ge₀.₉₂Sn₀.₀₈/Ge multiple-quantum-well photodetector on Si platform for SWIR detection

• Main Authors: Wu, Shaoteng, Xu, Shengqiang, Zhou, Hao, Jin, Yuhao, Chen, Qimiao, Huang, Yi-Chiau, Zhang, Lin, Gong, Xiao, Tan, Chuan Seng
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Electrical and electronic engineering; Germanium-tin; Semiconductor; Silicon Photonics; Infrared Detectors; Black Silicon
• Online Access: https://hdl.handle.net/10356/152766
• Institution: Nanyang Technological University

Recently, high-performance GeSn photodiodes with external light illuminated on the device top surface have been demonstrated on various platforms. However, for image sensing systems with a focal-plane array (FPA), the front-illuminated sensors usually suffer from area limitations. Here, we report high-performance back-illuminated Ge0.92Sn0.08/Ge multiple-quantum-well (MQW) p-i-n photodiode on 300-mm silicon substrate, which was realized entirely by complementary metal-oxide-semiconductor (CMOS) compatible processes. A broadband photo response between 1,000-2,200 nm was observed, and the responsivity is 0.2850 and 0.0085A/W at 1,550 and 2,000 nm, respectively. A specific detectivity larger than 109 cm∙Hz1/2/W was achieved between 1,050 and 1,900 nm, covering all the conventional telecommunication bands (O to U band). Furthermore, the influence of the anti-reflective layers also was studied in detail. The result shows the black Si surface enhances more photo current between 1,000-1,500 nm while the SiO2 layer (400-nm-thickness) increases more current beyond 1,500 nm. The 3-dB bandwidth was calculated to be up to 8 GHz for a mesa with a diameter of 20 μm at -2 V. Our experiments demonstrated the high-detectivity and high-speed back-illuminated GeSn/Ge MQW photodiode with the potential applications in image sensing systems operated in the short-wave infrared (SWIR) range.