Analysis of On-State Gate Current of AlGaN/GaN High-Electron-Mobility Transistor under Electrical and Thermal Stresses

Abstract

We have analyzed the on-state gate current of an AlGaN/GaN high-electron-mobility transistor (HEMT) by applying electrical and thermal stresses. The gate current shows a positive temperature dependence and its activation energy is less than the gate Schottky barrier height. This indicates that the gate current is a thermionic field emission and flows through a thinned AlGaN Schottky depletion layer by a tunneling or hopping mechanism. The depletion layer is considered to be thinned by the crystal defects created in the gate fabrication process. On the other hand, we have found that the gate current is decreased by applying a high electrical power under a high thermal stress. Strong electroluminescence can be observed by applying stress. These experimental results imply that the crystal defects are annealed out by the recombination-enhanced defect reaction mechanism induced by generated hot carriers. Therefore, the gate current is decreased by the reductions in the tunneling and hopping probability due to the expansion of the depletion layer.

Reliability Investigation of GaN HEMTs for MMICs Applications

“…Hayashi et al [8] reported a significant decrease in gate leakage current after applying a 30 min on-state stress on AlGaN/GaN HEMT. On the other hand, the changes in the other electrical characteristics were small.…”

Mechanism of high-fluence proton induced electrical degradation in AlGaN/GaN high-electron-mobility transistors

“…AlGaN=GaN high-electron-mobility transistors (HEMTs) have become attractive in power electronics, microwave, and low-noise operation owing to their remarkable advantages of high breakdown field, high carrier mobility, and high saturation velocity. [1][2][3][4][5][6] Such devices have potential in space application, for which radiation effects are important issues of concern. For example, a satellite located at any near-earth orbit will be exposed to a flux of high energy particles from galaxy cosmic rays, solar flares, and Van Allen Belts, among which protons are the most common.…”