HOT-ELECTRON LUMINESCENCE IN ZNS ALTERNATING-CURRENT THIN-FILM ELECTROLUMINESCENT DEVICES

Hot electron luminescence experiments are performed on ZnS alternating-current thin-film electroluminescent (ACTFEL) devices in order to determine the extent to which the electron distribution is heated. The luminescence spectrum is found to be broad and essentially featureless up to a high energy cutoff of approximately 3.7 eV, which is determined by optical absorption within the ZnS. This result indicates that under normal operating conditions in a ZnS ACTFEL device, a significant fraction of the electrons transported across the phosphor possess energies equal to or in excess of the ZnS band gap.