Abstract
We report a direct measurement of relative Mn electroluminescence (EL) efficiency in an ac EL device as a function of position normal to the ZnS film plane. The Mn EL efficiency decreases strongly with distance from the cathodic to anodic region of the ZnS layer. The cathodic‐to‐anodic efficiency ratio is about two orders of magnitude. In addition, the first ∼0.2 μm of ZnS deposited exhibits a significantly lower Mn EL efficiency relative to the remaining ZnS.