Hot-Electron Effects in GaN GITs and HD-GITs: A Comprehensive Analysis

We investigate the dc, electroluminescence (EL) and trapping properties of gate-injection transistors without and with the pdrain terminal connected to the drain (called GITs and HD-GITs respectively) and with and without field-plate. Our results indicate that: (i) the dc characteristics are not influenced by the presence of the pdrain terminal and of the field plate; (ii) EL measurements indicate that GITs and HD-GITs have comparable hot-electron density and energy. (iii) When submitted to OFF-state, all devices show similar dynamic-RON, independently of the presence of pdrain and field plate; (iv) on the other hand, under semi-ON trapping conditions substantial differences are observed. Specifically, the HD-GITs have a significantly lower dynamic-RON compared to GITs; a further improvement is obtained through the use of a field plate. (v) Transient RON measurements indicate that the traps filled are the same both under OFF-state and semi-ON conditions. The activation energy Ea of this trap is Ea∼0.8 eV, i.e. it could be ascribed to deep levels related to CN, as suggested also by pulsed measurements carried out under external illumination. Based on the original results collected within this paper, we conclude that the difference in dynamic-RON shown in semi-ON by GITs and HD-GITs is related to the injection of holes from the pdrain terminal that reduces the impact of hot-electron trapping processes.

I. Introduction

Power transistor based on gallium nitride (GaN) are emerging as excellent devices in the power electronics fields. This is because GaN has a wider bandgap, higher electron mobility, and higher critical electrical field when compared against conventional semiconductors [1].