Heterojunction p-Si/n-ZnO: Fabrication, Electrical Characterization and Its Applications as Ultraviolet Sensor

摘要

The fabrication and performance analysis of an ultraviolet photo-sensor based on p-Si/n-ZnO heterojunction diode is reported in this article. Nanocrystalline ZnO thin film of (～300 nm thickness) was deposited on p-Silicon wafer by radio frequency magnetron sputtering technique (RF). Morphological, structural and optical properties of deposited film was determined by Scanning Probe Microscopy (SPM), X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDS), Field Emission Scanning Electron Microscope (FESEM), and UV-visible spectroscopy respectively. From the XRD and SPM results it is shown that the fabricated thin film is polycrystalline nature (c-axis) and has low surface roughness. The obtained optical band gap of film was 3.35 eV. The electrical and photo response property of fabricated p-Si/n-ZnO heterojunction diode was confirmed by measuring I-V and C-V characteristics. The I-V characteristic of the heterojunction diode is asymmetrical with a rectification ratio of order three at ±2 V, turn-on voltage of 0.82 V and ideality factor of 6.15. It is also showed very good photoresponse with responsivity of 2.2 A/W under UV illumination (365 nm). The detectivity of the device is found to be 0.468 × 10~(-12) cmHz~(1/2)W~(-1). Comprehensive results suggested that the grown film is an excellent semiconductor material and proposed diode is alternative device for GaN based UV detector.