Abstract
This research work examines the structural and optical properties of ZnO thin films. Deposition were done by spin coating of solution of Zinc oxide onto pre-cleaned glass substrate at 4000 rpm for 30 sec using spin-coater under ambient condition at room temperature in order to form desired thickness of the film on the substrate. Post- deposition thermal annealing at different range of temperatures from 150°C to 600°C with steps of 50°C was carried out on the samples. The impact of thermal annealing on optical properties of the deposited thin film was investigated using UV-VIS spectrophotometer and scanning Electron Microscope for the morphology. The optical transmittance, reflectance, absorbance were recorded which was used to evaluate the optical band gap of Zinc oxide. Observation shows that band gap energy reduces as annealing temperature is increased from 150°C to 600°C. Observation made on the morphology using SEM model ASPEX 3020 showed that as the temperature increases the surface of the sample roughness increases. It was deduced that as the annealing temperature is increased the surface roughness increases. This may be due to increase in grain size with increase in annealing temperature. The band gap energy decreases as the annealing temperature increases.
Highlights
Zinc oxide (ZnO) is an important semiconductor material that has its found application in organic electronics such as solar cells and optoelectronics to mention but a few [1]
Zinc oxide is an inexpensive ntype semiconductor which can be used as electron transporting layer in solar cells because it has high thermal and mechanical stability at room temperature coupled with chemical stability
The photon absorption upon heating zinc oxide was highest at 500°C in the visible spectrum
Summary
Zinc oxide (ZnO) is an important semiconductor material that has its found application in organic electronics such as solar cells and optoelectronics to mention but a few [1]. Zinc oxide is an inexpensive ntype semiconductor which can be used as electron transporting layer in solar cells because it has high thermal and mechanical stability at room temperature coupled with chemical stability. It has broad range of radiation absorption and high photo stability. Zinc oxide (ZnO) is used as a heterogeneous catalyst, have a high catalytic activity, nontoxic, insoluble, and a cheap catalyst [3 -4] which is an important n-type [5-7] semiconductor. The interest in ZnO is as a result of its high abundance and the availability of potentially high quality low cost substrate layers of transparent ZnO films on which electronic processes solar cells and flat panel displays occur [21-30]
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