Investigation Of ZnO Nanostructures On Glass Substrate Deposited By Thermal Evaporation Method For UV Detection
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Date
2018-01
Authors
Abed, Forat Hamzah
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Abstract
In this work, ZnO nanostructures with different morphologies were fabricated on a cost-effective glass substrate using a simple thermal evaporation in a conventional horizontal tube furnace via vapor–solid (VS) and vapor–liquid–solid (VLS) mechanisms. This study aims to provide a new approach for synthesis of one-dimensional (1D) and three-dimensional (3D) ZnO nanostructures using a low cost substrate by thermal evaporation of Zn powder in the presence of O2 gas, and determine optimal parameters to control high crystal quality and optical properties, thereby improving the performance of ultraviolet (UV) photodetectors (PDs) based on the produced ZnO. First, using VS mechanism; catalyst-free growth of 3D ZnO tetrapods (Ts) was successfully conducted on glass substrate. Controlled synthesis of ZnO-Ts was achieved through glancing angle deposition by three-step directions of glass substrate with inclination angles of 0°, 45°, and 90° toward the gas flow, and through two growth temperature regions: 425-650 °C and 475-750 °C. Sputtered ITO thin film as a seed layer coated glass substrate, followed by seed annealing temperature using a continuous wave (CW) CO2 laser, employed here to seed/catalyst-free growth of ZnO-NW networks. The control of the length and diameter of the nanowires were systematically investigated by modifying seed laser annealing temperatures of 250, 350, and 450 °C, respectively. The growth mechanism of seed/catalyst-free ZnO-NW balls under intermittently pumped carrier gas as a new and simple nucleation method was investigated. Results showed that the proposed method facilitates epitaxial nucleation and growth of high-density vertically aligned ZnO-NWs with several micrometers in length and that have a smaller diameter and higher crystallization compared with those fabricated using traditional continuous pumping under the same growth condition.
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ZnO nanostructures on glass substrate deposited , thermal evaporation method for UV detection