You have to be more specific in what kind of properties you are looking for. Roughness even in the nanoscale can play an important role in several properties, i.e. optical, mechanical, wetting e.t.c. Also you have to state what is the roughness of the deposited film.

Film roughness is about 20-50nm and I am insterested in optical and mechanical properties. Mr Dimitrios

In that range of roughness I think optical properties will not be affected if we compare them to the optical properties of a flat film (

EM wave scattering is affected by roughness. Your range of roughness is however in the x-ray region of wavelength. I would wonder, compared to an atomically flat surface, whether you may see differences in the optical region as you go to grazing incidence, especially in polarization behavior.

*Definitely optical property of your thin film will be affected for the roughness range of 20-50 nm.

this paper may be helpful

Structure and optical properties of Ag–Al2O3 nanocermet solar selective

coatings prepared using unbalanced magnetron sputtering,

Solar Energy Materials& Solar Cells 95(2011)1707–1715

* nanoindenter hardness measuremet will help you to find the hardness variation on different spots of your thin film. this is mainly due to the different roughness on different spot.

so both optical and mechanical property will be affected for your film