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As one of the cornerstones of photoelectric detection system, ultraviolet (UV) detector has the ability to convert UV signal into electrical signal, which is widely used in optical communication, biomedicine, and other fields. NiO has a strong absorption of UV light due to its wide band gap of 3.4 to 4.1eV. In addition, NiO exhibits a p-type conduction at room temperature. Thus, it is often used to form a pn junction in combination with a n-type semiconductor for photodetection. Si has the unique advantages of being integrated and compatible with CMOS processes. By constructing the NiO/n-Si heterojunction, the advantages of Si and NiO can be combined to prepare high performance and low-cost UV detectors. However, most of the reported NiO/n-Si UV detectors showed large dark current and low UV responsivity. Besides the defects in the silicon and NiO, the thickness of NiO film is an important factor that affects the performance. Herein, the NiO/n-Si UV photovoltaic detectors with different NiO film thicknesses were fabricated. The effect of NiO film thicknesses, such as 32, 74, 113, 147, 198 and 270 nm, on the performance of NiO/n-Si UV detector was investigated. A NiO/n-Si UV detector with a NiO thickness of 198 nm showed the excellent performance with a low dark current of 0.6 μA at -1 V and a high rectification ratio of 1.8×104 at ±1 V. The maximum responsivity (R) and detectivity (D*) of the device were 1.3 A/W and 5.7×1011 Jones, respectively, under 365 nm UV illumination. This work demonstrated that controlling NiO thickness has an essential influence on the performance optimization of NiO/n-Si UV photovoltaic detector.
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