Polycrystalline films of ZnS with a slight excess of S were grown onto (100)Si by means of congruent sublimation from a single Knudsen cell. Intense blue emission was observed at 460nm in room-temperature photoluminescence studies, and was attributed to S-Zn vacancies which acted as self-activated centers. The emission was quenched by the addition of Zn from a second Knudsen cell, which also caused the growth of a luminescent peak that was centered on 678nm. No reduction in the self-activated luminescence was seen upon co-sublimating ZnS and AgS. This implied that it was not possible completely to remove the S vacancy. Quenching of the blue emission occurred when Mn, rather than Zn, was added to ZnS films. This provided direct evidence for Mn incorporation into Zn vacancies. At the optimum Mn concentration, the intensity of the Mn emission at 580nm was comparable to the blue emission (460nm) from undoped ZnS films.

I.P.McClean, C.B.Thomas: Semiconductor Science and Technology, 1992, 7[11], 1394-9