Effect of temperature on the electrical performance of GaN Schottky barrier impact ionization avalanche transit time diodes

Abstract

This article investigates the effect of temperature on GaN Schottky barrier Impact Ionization Avalanche Transit Time diodes by Sentaurus TCAD simulations. The findings indicate that Thermal Field Emission increases and the electron saturation velocity decreases with temperature, reducing the avalanche injection phase delay and leading to the transit phase delay exceeding its optimal value. These factors impair the performance of oscillation initiation and conversion output with a shift of bandwidth and optimal frequency towards lower values. Specifically, the start-up efficiency and speed decrease by 69% and 80%, while radio frequency power and efficiency drop by 32% and 41% at the design frequency of 120 GHz under 500 °C. Additionally, the proportion of radio frequency conversion power lost through parasitic resistance increases threefold, and the stability of radio frequency oscillations diminishes by 70%. Therefore, it is recommended to maintain a low junction temperature whenever possible to ensure optimal device performance. In cases where high junction temperatures are unavoidable, reducing the thickness of the drift layer can compensate for the excess transit phase delay, thereby improving performance.