Chun-Yan Wu, Zhi-Qiang Pan, You-Yi Wang, Cai-Wang Ge, Yong-Qiang Yu, Ji-Yu Xu, Li Wang, Lin-Bao Luo*
Abstract:  A highly sensitive near infrared light (NIR) photodetector was fabricated by coating a thin layer of Cu film onto vertical n-type SiNW arrays through a solution based reduction reaction. The as-fabricated core-shell SiNWs array/Cu Schottky junction exhibits an obvious rectifying behavior in dark with a turn-on voltage of ~0.5 V and a rectification ratio about 102 at ±1.5V. In addition, it shows a pronounced photovoltaic performance when illuminated by NIR light with wavelength of 980 nm. Such photovoltaic characteristic can allow the device to detector NIR illumination without exterior power supply. Further device analysis reveals that the self-powered NIR photodetector is capable of monitoring ultrafast optical signal with frequency as high as 30 kHz. What is more, the present device also has obvious advantages in responsivity, detectivity, on/off ratio, and response speed. Further theoretical simulation reveals that the good device performance is associated with the excellent optical and electrical property of core-shell heterojunction geometry.