WO3 thin films by spin coating technique and their wettability

Abstract

Preparation of tungsten trioxide, WO 3, thin films on c-Si substrates using sol-gel method from a precursor based on non-alkoxide materials has been done in this study. Differential scanning calorimetry, DSC, thermogravimetry, TGA, and differential thermal analysis, DTA, have been used to monitor structural changes during heating. Thermal analysis of the xerogel gives a clear idea about water evolving and phase change. X-ray diffraction, XRD, studies revealed that the film dried at 120 ˚C for 1h is non-crystalline. After heating at 700˚C for 2h, a monoclinic phase of WO 3 with preferred orientation along (200) direction appeared. Chemical bonding has been explored by Fourier transform infrared spectroscopy, FTIR. Surface roughness has been found to increase with the increase of annealing temperature as revealed from AFM measurements. At temperatures equal and above 700 ˚C, contact angle decreased due to surface roughness increase. Correlation between the characteristic properties and the contact angle measurements has been discussed.