The films of Tl doped CsI (CsI:Tl) of varying thicknesses ranging from 10 μm - 1.5 mm have been grown on silica glass substrates by thermal evaporation technique. Effects of substrate temperature, substrate surface texture and film thickness on the film structure and morphology were studied. The film shows a preferred orientation along the <200> direction having columns of diameter 1-6 μm depending on the film thickness. In the films of lower thicknesses a number of cracks were observed that vanishes with increase in the film thickness and shows a continuous and crack-free morphology beyond 500 μm thickness. Radio-luminescence of the films was also recorded using a white x-ray source (Cu target) and a solid state spectrometer in 300-800 nm wavelength range. © 2014 AIP Publishing LLC.