Structure-composition-property dependence in reactive magnetron sputtered ZnO thin films

Abstract

Thin films of zinc oxide (ZnO) were prepared by dc reactive magnetron sputtering on glass substrates at various oxygen partial pressures in the range 1 Â 10 À4 -6 Â 10 À3 mbar and substrate temperatures in the range 548-723 K. The variation of cathode potential of zinc target on the oxygen partial pressure was explained in terms of target poisoning effects. The stoichiometry of the films has improved with the increase in the oxygen partial pressure. The films were polycrystalline with wurtzite structure. The films formed at higher substrate temperatures were (0 0 2) oriented. The temperature dependence of Hall mobility of the films formed at various substrate temperatures indicated that the grain boundary scattering of charge carriers was predominant electrical conduction mechanism in these films. The optical band gap of the films increased with the increase of substrate temperature. The ZnO films formed under optimized oxygen partial pressure of 1 Â 10 À3 mbar and substrate temperature of 663 K exhibited low electrical resistivity of 6:9 Â 10 À2 X cm, high visible optical transmittance of 83%, optical band gap of 3.28 eV and a figure of merit of 78 X À1 cm À1 . Ó

Effects of substrate position and oxygen gas flow rate on the properties of ZnO: Al films prepared by reactive co-sputtering

“…The electrical properties of ZnO: Al films are expected to be mainly influenced by the Al enrichment level, the grain size, the oxygen stoichiometry and the substrate temperature [6][7][8]. This section discusses the characteristics of the films in connection with the deposition parameters.…”

“…This can be ascribed to an increase of receptive surface areas and more marked getter effect [15] as Dts increases. In the case of undoped ZnO synthesized at high pressure (2 Pa), the lowest electrical resistivity (ρ = 8.2 Ω cm) is observed for the stoichiometric films [6] with enhancement as the oxygen partial pressure increases over a critical value of 10 − 1 Pa, corresponding to the start of the Zn target Compound Sputtering Regime (CSR). Whatever the Al doping effect, the same type of behaviour is observed for the coatings of the present study when the substrates are placed far from the magnetron axis (Fig.…”

Preparation of highly textured surface ZnO thin films

“…ZnO thin films with refractive index in the order of 1.97 can play this double role if it can be obtained with higher surface roughness. ZnO thin films can be deposited by various methods including sputtering [10][11][12][13][14], spray pyrolysis [15][16][17], sol-gel [18] pulse laser deposition [19] chemical vapor deposition (CVD) [20].…”

Effects of substrate temperature on sprayed ZnO thin films optical and morphological properties in terms of Amlouk–Boubaker opto-thermal expansivity ψAB

“…It was reported [11] that ZnO film structure depends wholly on elaboration technique, substrate material and thermal treatment conditions. This feature was also discussed by Yang et al [12] who presented temperature-dependent structure alteration of the ZnO layers It is obvious that, according to the peak angles shifting towards both (0 0 2) and (1 0 1) orientations, which are characteristics to ZnO pillar crystal structures, the temperature effect results in a more transparent crystalline structure.…”