@article{Sangwan2021, 
author = {Vinod K. Sangwan and Joohoon Kang and David Lam and J. Tyler Gish and Spencer A. Wells and Jan Luxa and James P. Male and G. Jeffrey Snyder and Zdeněk Sofer and Mark C. Hersam},
title = {Intrinsic carrier multiplication in layered Bi2O2Se avalanche photodiodes with gain bandwidth product exceeding 1 GHz},
year = {2021},
journal = {Nano Research},
volume = {14},
number = {6},
pages = {1961-1966},
keywords = {high-frequency, photodetector, impact ionization, layered semiconductor, Schottky diode},
url = {https://www.sciopen.com/article/10.1007/s12274-020-3059-3},
doi = {10.1007/s12274-020-3059-3},
abstract = {Emerging layered semiconductors present multiple advantages for optoelectronic technologies including high carrier mobilities, strong light-matter interactions, and tunable optical absorption and emission. Here, metal-semiconductor-metal avalanche photodiodes (APDs) are fabricated from Bi2O2Se crystals, which consist of electrostatically bound [Bi2O2]2+ and [Se]2- layers. The resulting APDs possess an intrinsic carrier multiplication factor up to 400 at 7 K with a responsivity gain exceeding 3,000 A/W and bandwidth of ~ 400 kHz at a visible wavelength of 515.6 nm, ultimately resulting in a gain bandwidth product exceeding 1 GHz. Due to exceptionally low dark currents, Bi2O2Se APDs also yield high detectivities up to 4.6 × 1014 Jones. A systematic analysis of the photocurrent temperature and bias dependence reveals that the carrier multiplication process in Bi2O2Se APDs is consistent with a reverse biased Schottky diode model with a barrier height of ~ 44 meV, in contrast to the charge trapping extrinsic gain mechanism that dominates most layered semiconductor phototransistors. In this manner, layered Bi2O2Se APDs provide a unique platform that can be exploited in a diverse range of high-performance photodetector applications.}
}