May be it is amorphous. Have you checked the X-ray diffraction, to see if the deposited film is crystalline and conforms to crystalline SnO2

Prof. Sreenivas gives you a good idea, you can use X-ray diffraction.

At very first for structural studies, you need to conduct XRD, definitely you can get those peaks. Of course, Raman is parallel to the X- ray diffraction.

The basic characterization technique to check whether the sample has been synthesized properly or not is by using XRD technique i.e X-ray diffraction. Match the data you obtain with the JCPDS card mentioned in the literatures of the same compound. If the result shows desired peaks then go for Raman Spectroscopy and other charecterizations.