High-performance n-V2O5/p-Si heterojunction photodetector prepared by pulsed laser deposition: role of laser fluence
摘要
In this study, a n-V2O5/p-Si heterojunction photodetector was fabricated using pulsed laser deposition (PLD) technique. The structural, electrical, and optical properties of the V2O5 thin film were examined as a function of laser fluence. X-ray diffraction studies reveal that the deposited V2O5 films are crystalline with an orthorhombic structure, and the crystallinity of the films was found to depend on laser fluence. The optical properties show that the energy gap of the V2O5 film decreases from 2.7 to 2.1 eV as the laser fluence increases from 6.36 to 8.91 J/cm2. Scanning electron microscopy investigations show the formation of compact films, and the grain size increases as the laser fluence increases. Photoluminescence studies reveal the presence of two emission peaks at 375 and 460 nm, with a slight shift toward longer wavelengths as the laser fluence increases. The current–voltage characteristics of n-V2O5/p-Si heterojunction photodetectors under both dark and illuminated were analyzed as a function of laser fluence. The photodetectors demonstrate a rectification characteristic, and the ideality factor of the heterojunctions prepared at 6.3, 7.64, and 8.91 J/cm2 was 4.3, 2.8, and 9.9, respectively. The maximum responsivity was 2.96 A/W at 500 nm for the photodetector deposited at 7.64 J/cm2. The photodetector fabricated at 7.64 J/cm2 exhibits the highest detectivity and external quantum efficiency, achieving 1.35 × 1013 Jones at 500 nm and 7.96 × 102% at 450 nm, respectively. Additionally, an illuminated energy band diagram of V2O5/Si fabricated at 7.64 J/cm2 was developed.