Abstract Zinc sulfide (ZnS) is a wide-bandgap compound semiconductor that is broadly used for various micro- and opto-electronic applications. ZnS is also applied as an emitter layer in thin-film photovoltaic devices. The preparation of thin-film photovoltaic devices requires suitable methods for doping semiconductor layers up to the desired level. For this purpose, in the present work, an ion assisted deposition system was developed and evaluated. We used a combination of simple thermal vacuum evaporation coupled with plasma discharge in the reactive gas. The results of this study show that the developed deposition system allows for in-situ doping control of ZnS thin films.