Crystallography and morphology dependence of In2O3:Sn thin films on deposition rate

Abstract

In2O3:Sn (ITO) thin films with thickness of 200nm were grown on glass substrates by electron beam evaporation method at different deposition rates. The deposition rate was adjusted in the range between 3nm/min and 12nm/min. X-ray diffraction (XRD) analyses indicate that the ITO films are polycrystalline, having a body-centered cubic (BCC) structure irrespective of their deposition rate. All ITO films showed preferred orientation along the (2 2 2) crystalline plane. The microstructural parameters such as grain size (D), lattice constant (a0), lattice strain (ε) and dislocation density (δ) were calculated. It is found that the deposition rate has an important role in controlling the microstructural parameters of ITO thin films. Surface morphology of the ITO thin films was studied using atomic force microscopy (AFM). The quantitative AFM characterization showed that the root mean square (RMS) surface roughness of the films decreases monotonically with increasing the deposition rate. The film deposited at lower growth rate has larger grains, and a larger grain size appears to correspond to a higher film surface roughness. Under optimized deposition conditions, an electrical resistivity of 3.04×10−4Ωcm with RMS surface roughness of 4.41nm was achieved for lower deposition rate 3nm/min. Also, the film surface morphology does not directly affect the structural properties of the prepared ITO thin films.