Evidence of donor center involvement in ac thin film electroluminescent devices exhibiting memory

Alternating current thin film electroluminescent (EL) devices exhibiting memory with low Mn concentrations have a temperature independent threshold, but a temperature dependent saturation brightness and memory margin. Based upon these observations we argue that EL emission is initiated via the usual tunneling process from interface states, but subsequent characteristics are determined via a second carrier generation process. Shallow donor sites are calculated to exist at a depth of 0.12 eV below the conduction band. These are believed to be involved in the second carrier generation process since brightness‐voltage characteristics are associated with Poole–Frenkel emission.