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.
Silicon (Si) based photodetectors have been widely used in numerous applications due to their low-cost, high efficiency and good process compatibility. In this paper, a photodetector based on Si mesa heterojunction is reported. Si was doped by ion implantation and used to fabricate a photodetector. The conditions of ion implantation were simulated using a software to obtain the required process parameters before the commencement of the implantation process. The process involved deposition of 100 nm SiO2 film on to the Si substrate, and B ions were injected with 160 keV energy, 6×1014 cm-2 injection dose and at 7° dip angle. After ion implantation, the material was annealed at 900 ℃ for 30 min to repair crystal damages and activate the impurity level. Subsequently, a Si-based mesa heterojunction photodetector was fabricated using a series of standard processes. The photosensitive area of each device unit was 2.04 × 10-2 mm2 . The responsivity of the photodetector in the near ultraviolet and visible bands was more than 0.14 A/W under the bias of -2V. The responsivity of the device was measured using a 1073 K blackbody source, and the voltage responsivity of the blackbody was 1.35×102 V/W. Results from the C-V measurements revealed that the Si has a carrier concentration in the order of 1019 cm-3, which is in good agreement with the simulated results. The experimental results showed that ion implantation has an important effect on the electronic properties of the material and can greatly improve the photoelectric properties of devices.
Silicon has been widely used in the field of low-cost photodetectors. However, the use of traditional silicon material for high performance infrared detectors is hindered by its indirect band gap. Recently, black silicon has attracted the attention of researchers working on optoelectronics as it can be considered a new type of material with high absorption, and expansion of the response band can be achieved by supersaturated doping. Importantly the material is compatible with the silicon process. With the development of science and technology, the application of photodetectors can have a great impact on our lives, so the research on black silicon photodetectors is also becoming popular. Up to now, significant progress has been made in the development of black silicon photodetectors. This paper summarizes the preparation of black silicon materials and the application prospect of black silicon photodetectors.
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