Comparative study of the crystal phase,crystallite size and microstrain in electroluminescent ZnS:Mn films grown by atomic layer epitaxy and electron beam evaporation

The crystallite size, the microstrain and their dependence on the thickness of the active layer in electroluminescent ZnS:Mn thin films were studied by X-ray diffraction line profile analysis. The average crystallite size in the films grown by atomic layer epitaxy (ALE) is about 100 nm, which is larger than that for films deposited by electron beam evaporation (EBE) by a factor of 5–10. In addition, the relative microstrain in the films prepared by EBE was about six times that in the films grown by ALE. The comparison is made using the average crystallite size values for both types of sample. Also the crystal phase and dislocation density were clearly different in the two types of the thin film. It is suggested that the large crystallite size and therefore the low density of crystallite boundaries are very probably causes of the observed increase in electroluminescent efficiency.