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E4.10.1

Structural and Optical Properties of Thin Metal-Oxide Films (ZnO and SnOx) Deposited on Glass and Silicon Substrates Serekbol Zh. Tokmoldin, Bulat N. Mukashev, Nurzhan B. Beisenkhanov, Azamat B. Aimagambetov and Irina V. Ovcharenko Institute of Physics and Technology, Almaty, 050032, Kazakstan ABSTRACT Thin ZnO films deposited on silicon and glass substrates by DC reactive magnetron sputtering were exposed to a sequence of thermal treatments at 400°C in vacuum, then in air, then in vacuum again. Photoluminescence studies of these ZnO films exited at 325 nm by He-Cd laser revealed an appearance of a photoluminescence band around 380 nm upon the annealing in vacuum. Thin SnOx films were deposited on glass substrates by ion-beam sputtering using pure oxygen as a working gas. X-ray diffraction analysis showed that as-deposited films consist of textured SnO2- and Sn2O3-crystallites which are transformed into polycrystalline SnO2 phase at a moderate temperature near 200°C. It is shown that the growth of the SnO2 crystallite size upon the annealing is mainly due to the disappearance of an amorphous phase at 400°C and coalescence of crystallites at 600°C.

INTRODUCTION ZnO is promising for various technological applications, especially for optoelectronic, due to its piezoelectric properties, high electron conductivity and good optical transparency [1]. These properties along with the wide direct band gap (3.37 eV) make ZnO a very good prospect for semiconductor sources of both visible and ultra-violet radiation. Among various methods the reactive magnetron sputtering is a promising technique to grow thin ZnO films [2-4]. Electrical conductivity of ZnO films measured immediately after deposition has an irreversible dependence on the annealing temperature which may be explained by transformation of the film structure [3]. After a sequence of heating and cooling the temperature dependence of the electrical conductivity becomes reversible [3,4]. Exciton photoluminescence is very sensitive to defects and quality of crystal structure [5]. Good polycrystalline structure of coarse grained ZnO film upon the annealing at 700°C [1] enables the appearance of an ultra-violet exciton photoluminescence band at 80K. Thin SnO2 films are good prospect for making sensors for ecological monitoring of environment, for explosive and poisonous gases leakage control, etc. [6]. The properties of the films depend on the deviation from stoichiometry, microstructure, doping and contaminations [78]. An interesting topic is the influence of microstructure on electrical and optical properties of SnOx films. It was shown that the increase of annealing temperature results in the growth of both SnO2 grain sizes [7,9] and electrical conductivity of films [7,10]. In this paper photoluminescence and X-ray studies of thin ZnO films on the silicon and polished and chemically cleaned glass substrates and SnOx films on the glass substrate deposited by ion-beam technique were carried out.

E4.10.2

EXPERIMENTAL DETAILS Thin ZnO films were deposited on sil