A combined sintering-sublimation method has been used to grow CdS or CdSeS photo-conducting polycrystalline thin films. By a fast firing technique, the films are grown on Cr2O3-x ceramic pellet sintered substrate. The film growing and the fast firing sintering processes take place simultaneously. The sintering-sublimation technique has been designed to increase the reliability of photoconducting devices, mainly by decreasing the donors' concentration which determines a higher sensitivity. This process becomes more effective when pellets containing raw CdS, respectively CdSeS, and a less reactive component - such as nonstoichiometric chromium oxide, are used. This oxide provides surfaces where thin CdS or CdSeS layers are crystallizing. At the same time, the nonstoichiometric Cr2O3-x can react with the oxygen allowing a more efficient control of the properties of CdS and CdSeS thin layer which is generated as a result of the above-mentioned sublimation-condensation process.