Thin films of undoped and tin‐doped In2O3have been investigated for use as plasma filters in spectral control applications for thermal photovoltaic cells. These films are required to exhibit high reflectance at wavelengths longer than the plasma wavelength &lgr;p, high transmittance at wavelengths shorter than &lgr;pand low absorption throughout the spectrum. Both types of films were grown via atmospheric pressure chemical vapor deposition (APCVD) on Si (100) and fused silica substrates using trimethylindium (TMI), tetraethyltin (TET), and oxygen as the precursors. The O2/TMI partial pressure ratio and substrate temperature were systematically varied to control the filter characteristics. The plasma wavelength &lgr;pwas found to be a sensitive function of the O2partial pressure and the substrate temperature. Post‐growth annealing of the films carried out either in nitrogen or air ambient at elevated temperatures did not have any beneficial effect. Tin‐doped In2O3was grown using tetraethyltin (TET) as the dopant. The material properties and consequently the optical response were found to be strongly dependent on the growth conditions such as O2and TET partial pressures. Both undoped and tin‐doped In2O3grown on fused silica exhibited enhanced transmittance due to the close matching of refractive indices of In2O3and silica. X‐ray diffractometer measurements indicated that all these films were polycrystalline and highly textured towards the (111) direction. The best undoped and tin‐doped In2O3films had a &lgr;paround 2.7 &mgr;m, peak reflectance greater than 75% and residual absorption below 20%. These results indicate the promise of undoped and tin‐doped In2O3as a material for plasma filters. ©1996 American Institute of Physics.