Sub-Bandgap Photo-Response of Chromium Hyperdoped Black Silicon Photodetector Fabricated by Femtosecond Laser Pulses

• Published in: IEEE sensors journal 2021-11, Vol.21 (22), p.25695-25702
• Main Authors: Li, Chao, Zhao, Ji-Hong, Yang, Yang, Chen, Qi-Dai, Chen, Zhan-Guo, Sun, Hong-Bo
• Format: Article
• Language: English
• Subjects: Absorptance; Absorption; Absorptivity; Annealing; Atomic beams; Black silicon; Chromium; Conduction bands; Delay time; Energy gap; Energy levels; femtosecond laser pulses; Femtosecond pulses; hyperdoping; Impurities; infrared absorption; Infrared radiation; Integrated circuits; photodetection; Photodiodes; Photometers; Silicon; Substrates
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2021.3119020

As the main component of silicon (Si)-based Optic Electronics Integrated Circuit (OEIC) chip, Si-based infrared photodetector operating at communication wavebands is very important. In this paper, we report a kind of chromium (Cr)-hyperdoped black Si material fabricated using femtosecond laser pulses irradiation. The concentration of the Cr atoms in the black Si layer exceeds 10 20 cm −3 and the Cr-hyperdoped Si has a large sub-bandgap absorptance (~60% for 1.31 \boldsymbol {\mu }\text{m} ). The deep-energy level introduced by Cr impurity is 0.39 eV below the bottom of conduction band and thus the ionized electron concentration is very low (~10 15 cm −3 ). Owing to the excellent sub-bandgap absorption of Cr-hyperdoped Si, face-to-face black Si photodiodes are fabricated. Under illumination of 1.31 \boldsymbol {\mu }\text{m} light, the responsivity of the photodiodes based on N + -N junction reaches 0.57 A/W at 4.3 V bias. In addition, the rise and delay time of the device to the infrared light are on the order of milliseconds.