Ultra-violet photo-response characteristics of p-Si/i-SiO2/n-ZnO heterojunctions based on hydrothermal ZnO nanorods. (1st August 2017)

• Record Type: Journal Article
• Authors: Khan, Waqar; Kim, Sam-Dong
• Is Part Of: Materials science in semiconductor processing. Volume 66(2017)
• Page Start: 232
• Page End: 240
• Publication Date: 2017-08-01
• Subjects: ZnO nanorod -- Seed layer -- Hydrothermal growth -- I-V characteristics -- Structural properties -- Optical properties -- Rectification ratio -- Ideality factor -- Photo response transient; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2017.04.031
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: Hydrothermal zinc oxide (ZnO) nanorod (NR)-based p -Si/ n -ZnO and p -Si/ i -SiO2 / n -ZnO heterojunctions were fabricated, and the effects of interfacial native SiO2 (~4 nm) on the I-V characteristics of heterojunctions under dark and ultra-violet illumination conditions were investigated. First, the structural and optical properties of ZnO seed crystals grown by sol-gel method and hydrothermal ZnO NRs on two different substrates of p -Si and p -Si/ i -SiO2 were examined, and more improved optical and crystalline quality was obtained as revealed by photoluminescence and X-ray diffraction. The p-i-n heterojunctions showed ~3 times greater forward-bias currents and enhanced rectifying property than those of p-n junctions, which is attributed to the role of native SiO2 in carrier confinement by promoting the electron-hole recombination current through the deep level states of ZnO crystal. The measured ratios of photocurrent to dark current of the p-i-n structure were also greater under reverse bias (92–260) and forward bias (2.3–7.1) conditions than those (28–225 for reverse bias, 1.6–6.8 for forward bias) of p-n structure, and the improved photosensitivity of the p-i-n structure under reverse bias is due to lower density of recombination centers in the ZnO NR crystals. Fabricated ZnO NR heterojunction showed repeatable and fast photo-response transients under forward bias condition of which response and recovery times were 7.2 and 3.5 s for p-i-n and 4.3 and 1.7 s for p-n structures, respectively.