Voltage-Current Characteristics for Electrical Conduction Through Thin MgO Films

Abstract

The voltage‐current characteristics of Au–MgO–Au thin‐film emission diodes formed by electron beam evaporation of Au and MgO are consistent with an expression derived for Schottky field emission into the conduction band of the oxide. These results however indicate a potential barrier height of about 0.72 eV when determined from the zero‐field intercept of the straight line logI vs V^1/2 plot and about 0.33 eV when obtained from an Arrhenius plot. These apparent barrier heights were different for devices fabricated by depositing the MgO film in an oxygen atmosphere. The apparent barrier height determined from the zero‐field intercept went up for increasing oxygen pressure and the barrier height determined from the Arrhenius plot went down. Emission of electrons into vacuum was observed from each device at very low sample biases indicating that preferential emission through pinholes in the Au overlayer was occurring.