Enhanced near-infrared responsivity of silicon photodetector by the impurity photovoltaic effect**Project supported by the National Natural Science Foundation of China (Grant Nos. 61464007, 61306084, and 51361022), the Postdoctoral Science Foundation of Jiangxi Province, China (Grant No. 2014KY32), and the Natural Science Foundation of Jiangxi Province, China (Grant No. 20122BAB202002).

Abstract

The near-infrared responsivity of a silicon photodetector employing the impurity photovoltaic (IPV) effect is investigated with a numerical method. The improvement of the responsivity can reach 0.358 A/W at a wavelength of about 1200 nm, and its corresponding quantum efficiency is 41.1%. The origin of the enhanced responsivity is attributed to the absorption of sub-bandgap photons, which results in the carrier transition from the impurity energy level to the conduction band. The results indicate that the IPV effect may provide a general approach to enhancing the responsivity of photodetectors.