Intrinsic carrier multiplication in layered Bi2O2Se avalanche photodiodes with gain bandwidth product exceeding 1 GHz

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 similar to 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 x 10(14) 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 similar to 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.

Automated summary

Bi2O2Se APDs exhibit high sensitivity and bandwidth, characterized by a unique reverse biased Schottky diode model, suitable for a diverse range of high-performance photodetector applications.