A comparative study of the ZnO Fibers-based photodetectors on n-Si and p-Si

The ZnO fibers (Fs)/p-Si (labeled D1) and ZnO Fs/n-Si (labeled D2) photodetector heterojunctions were fabricated and both devices gave a clear rectifying I-V characteristic with a high rectifying ratio, in the dark. At zero bias, D1 showed self-driven characteristics, while D2 had not and D1 was found to be more stable than D2 in time-dependent measurements. Optoelectronics results revealed that D1 had high sensitivity to both visible and excellent stability after 20 days. At zero bias, the ON/OFF ratio of the D1 photodetector was as high as 33 650 and in the dark, a rectification ratio of 67 400 within +/- 2 V was obtained for the D1 device. The maximum responsivities of the devices was similar to 0.8 mA W-1, and their detectivity was similar to 10(9) Jones. Furthermore, the ZnO Fs/p-Si (labeled D3) and ZnO Fs/n-Si (labeled D3) photodetectors yielded excellent response to 365 nm and 395 nm UV light (10 mW cm(-2)). Responsivity, detectivity (D), and external quantum efficiency values reached as high as 5.28 A W-1, 1.02 x 10(13) Jones, and %16.6, respectively under 365 nm UV light. The excellent responses of the photodetectors to visible and UV light were attributed to the oxygen vacancies in ZnO and the formation of electron-hole pairs by the light effect and their separation by the electric field in the device formed between ZnO and Si.

Automated summary

The ZnO fibers/p-Si and ZnO fibers/n-Si photodetector heterojunctions were fabricated and studied. Both devices exhibited good rectifying characteristics and high rectifying ratio in the dark. Among them, the D1 device showed self-driven characteristics and higher stability, maintaining excellent sensitivity and stability even after 20 days. The D3 device demonstrated good response to 365 nm and 395 nm UV light.