High-Performance Spray-Deposited Indium Doped ZnO Thin Film: Structural, Morphological, Electrical, Optical, and Photoluminescence Study

In this study, high-quality indium doped zinc oxide thin films were deposited using the spray pyrolysis technique, and the substrate temperature varied from 450A degrees C to 550A degrees C with steps of 25A degrees C with the aim of investigating the effect of substrate temperature. It was found that as the temperature increased, the resistivity of the films decreased to the extent that it was as low as 5.34 x 10(-3) Omega cm for the one deposited at 500A degrees C; however, it slightly increased for the resulting film at 550A degrees C. Although the carrier concentration mostly increased with temperature, it appeared that the carrier mobility was the parameter mainly governing the conductivity variation. In addition, the average transparency of the deposited films at 500A degrees C, 525A degrees C and 550A degrees C was around 87% (400-800 nm), which makes them outstanding transparent conductive oxide films. Moreover, the crystallite size and strain of the resulting films were estimated via the Williamson-Hall method. The results revealed a considerable reduction in the crystallite size and strain up to 500A degrees C followed by a rise at higher substrate temperature. Based on both the surface and cross-section field emission scanning electron microscope images, the film resulting at 500A degrees C was highly compacted and crack free, which can explain the enlargement of the carrier mobility (10.9 cm(2) V-1 s(-1)) in this film. Finally, a detailed photoluminescence study revealed several peaks in the spectrum and the variation of the two major peaks appeared to have correlation with the carrier concentration.