Sensitivity of the dynamic work function shift and emission current on device parameters in a new cold cathode design

Abstract

Recently, we analyzed a new cold cathode emitter which consists of a thin wide bandgap semiconductor material sandwiched between a metallic material and a low workfunction semimetallic thin film. Potential material candidates were suggested to achieve low voltage (<20 V), room-temperature cold cathode operation with emission currents of several hundred A/cm/sup 2/ and large efficiencies. We showed that under forward bias operation the electrons captured in the low work function material are responsible for an effective reduction of the semimetallic film work function together with a substantial increase of the cathode emitted current. This dynamic work function shift was shown to increase with the amount of injected current. Here, we study the bias dependence of the emitted current density in various device and physical parameters such as size of the emitter window, thickness of the wide bandgap semiconductor, electron mean free path in the semimetallic thin film, and probability of transmission across the various interfaces. We also analyze the lateral potential drop which would occur across the emission window of the structure and describe its effects on the emitted current density. This analysis provides a guide for better design of the proposed cold cathode structure.