DC Electroluminescence on M-I-S Structures in Thin Films

Abstract

Stable d.c. electroluminescence is observed in a cell with M-I-S structures in the form of thin films (Ta–Ta2O5–ZnS: TbF3–Au). To be able to observe d.c. electroluminescence in the cell, the Ta2O5 insulating layer must be about 1000 Å–5000 Å thick and treated by heating in air at 250°C for about 10 minutes. Through such heat treatment, the d.c. conductance of the Ta2O5 layer increases remarkably (about 103 times). The increase is due to the transition from an anomalous Poole-Frenkel effect to a normal one in the conduction process. This heat-treated Ta2O5 layer plays an important role in the creation of hot electrons required to excite the electroluminescent cell.