High-Performance Back-Illuminated Ge0.92Sn0.08/Ge Multiple-Quantum-Well Photodetector on Si Platform For SWIR Detection

• Published in: IEEE journal of selected topics in quantum electronics Vol. 28; no. 2: Optical Detectors; pp. 1 - 9
• Main Authors: Wu, Shaoteng, Xu, Shengqiang, Zhou, Hao, Jin, Yuhao, Chen, Qimiao, Huang, Yi-Chiau, Zhang, Lin, Gong, Xiao, Tan, Chuan Seng
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-03-2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Broadband; CMOS; Dark current; Diameters; Focal plane devices; Germanium; germanium alloys; image sensors; infrared detectors; Intermetallic compounds; Optical fibers; p-i-n photodiodes; Photodiodes; Photoelectric effect; Photoelectric emission; Quantum well devices; Quantum wells; Sensor arrays; Sensors; Short wave radiation; Silicon; Silicon dioxide; Silicon photonics; Silicon substrates; Substrates; Thickness
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2021.3078894

Recently, high-performance GeSn photodiodes (PDs) with external light illuminated on the device's 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 Ge 0.92 Sn 0.08 /Ge multiple-quantum-well (MQW) p-i-n PD on 300-mm silicon substrate, which was realized entirely by complementary metal-oxide-semiconductor (CMOS) compatible processes. A broadband photoresponse between 1,000-2,100 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 10 9  cm·Hz 1/2 /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 (b-Si) surface enhances more photocurrent between 1,000-1,500 nm while the SiO 2 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 PD with the potential applications in image sensing systems operated in the short-wave infrared (SWIR) range.