Temperature-Dependent Properties of Spray-Deposited ITO Thin Films
- PDF / 1,642,465 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 56 Downloads / 205 Views
.V. Moholkar, S.M. Pawar, K.Y. Rajpure, P.S. Patil, C.H. Bhosale, and J.H. Kim (Submitted January 17, 2009; in revised form July 16, 2009) Sprayed indium tin oxide (ITO) thin films are synthesized by mixing adequate quantities of ethanolic solutions of indium trichloride and stannic chloride at different substrate temperatures. The pyrolytic decomposition temperature affects the properties and morphology of ITO samples. X-ray diffraction results showed that the films are polycrystalline with cubic structure and exhibit preferential orientation along (222) plane. The SEM and AFM studies indicated that the surface morphology of the samples increases with substrate temperature. The typical I500 sample is composed of cubic grains and has carrier concentration of 3.26 3 1020 cm23 and mobility of 9.77 cm2/V s. The electrical resistivity of ITO films decreased with increasing deposition temperature. The highest figure of merit of film is 4.4 3 1023 X21. Optical absorption studies reveal that films are highly transparent in the visible region and band gap increases with substrate temperature owing to Moss-Burstein effect.
Keywords
atomic force microscopy, oxides, semiconducting materials, x-ray diffraction
1. Introduction Recent optoelectronic applications require improvements in the physical and chemical properties of transparent conducting oxides (TCOs) thin films. Among different TCOs, namely SnO2:F (FTO), SnO2:Sb (ATO), ZnO:Al (AZO), ZnO:Ga (GZO), In2O3:Sn (ITO) has the unique characteristics such as highest electrical conductivity, high optical transmittance over the visible wavelength region, and excellent adhesion to the substrates. These films are used in a number of applications, namely flat-screen high-definition televisions, high-resolution screens on portable computers, electrochromic windows, handheld new smart displays, optoelectronics, flat panel displays, solar cells, gas sensors, photo-catalysts, photoelectric-catalysis, etc. (Ref 1-3). TCO films can be n- or p-type semiconductor depending upon incorporated donor impurity (Ref 4, 5). The influence of microstructure and composition on the electrical and optical properties of ITO thin films is reported (Ref 6). Various deposition techniques have been widely used to produce ITO thin films. However, seeking the most reliable and economic deposition technique is the main goal. The most intensively
studied techniques are spray pyrolysis (Ref 7-16), sol-gel process (Ref 17), RF sputtering (Ref 18), evaporation (Ref 19), magnetron sputtering (Ref 20), electron beam evaporation (Ref 21), and pulsed laser deposition (Ref 22). The spray pyrolysis is one of the simplest deposition techniques because of its simplicity and it provides large area coatings without high vacuum ambience. So the capital cost and the production cost of high quality metal oxide thin films are expected to be the lowest among all the thin film deposition techniques. Furthermore, this technique is also compatible with mass production system. Also, the coatings produced with the spray pyrolysis
Data Loading...
