The deposition of zinc sulfide films (16) using dimethylzinc (46) and hydrogen sulfide (44) in a vacuum processor reactor (50) provides a low temperature process applicable for high volume production of infrared focal planes. These layers (16) of zinc sulfide are used as insulators and infrared anti-reflective coatings which are free of contamination relative to physical vapor deposited ZnS films. The zinc sulfide layers (16) are formed by evacuating a chamber (62) and mixing hydrogen sulfide gas (44) and dimethylzinc gas (46) at specific operating conditions until the desired ZnS film thickness is obtained. The rate of growth of the zinc sulfide (16) film is controlled by varying the temperature, pressure, and the relative flow rates of the hydrogen sulfide gas (44) and the dimethylzinc gas (46).