The effect of growth parameters on the deposition of CaS thin films by atomic layer epitaxy

Ca(thd)2 (thd = 2,2,6,6-tetramethyl-3,5-heptanedione) and H2S were used as precursors for the deposition of CaS thin films by atomic layer epitaxy (ALE). The growth on soda lime glass with and without alumina coating was studied by varying source furnace and substrate temperatures. In addition, the Ca(thd)2 and H2S pulse and purge times as well as the total number of ALE cycles were varied to observe their influence on the growth. A narrow processing window for the ALE growth was found when the source and substrate temperatures were 180–200°C and 325–400°C, respectively. The CaS thin films processed under optimized conditions were crystalline and smooth.