Abstract
The purpose of this work was to investigate the validity of Arrhenius accelerated-life testing when applied to gallium nitride (GaN) high electron mobility transistors (HEMT) lifetime assessments, where the standard assumption is that only critical stressor is temperature, which is derived from operating power, device channel-case, thermal resistance, and baseplate temperature. We found that power or temperature alone could not explain difference in observed degradation, and that accelerated life tests employed by industry can benefit by considering the impact of accelerating factors besides temperature. Specifically, we found that the voltage used to reach a desired power dissipation is important, and also that temperature acceleration alone or voltage alone (without much power dissipation) is insufficient to assess lifetime at operating conditions.
Highlights
Gallium nitride (GaN) high electron mobility transistors (HEMTs) offer gains in increased capability and lower costs due to their ability to operate at high power, high frequencies, and high temperatures [1]
Tested devices came from the same lot and had the same structure, which consisted of a semi-insulating silicon carbide (SiC) substrate [13], one 0.5-μm length optically defined gate with a gate-integrated field plate [13], and a source-connected field plate [4]
We have studied the degradation of AlGaN/gallium nitride (GaN) HEMTs subjected to the conditions of high
Summary
Gallium nitride (GaN) high electron mobility transistors (HEMTs) offer gains in increased capability and lower costs due to their ability to operate at high power, high frequencies, and high temperatures [1]. Extremely attractive for many U.S Department of Defense applications, insertion of this emerging technology is risky because of the little to no long-term use data that ensures the needed lifetimes are possible. Most estimates of GaN HEMT lifetimes have used conventional temperature-accelerated direct current (DC) operational-life test predictions. The Arrhenius extrapolations reported in the literature [2,3,4] have extremely long predicted median times to failure. The long estimates and high activation energies may not be indicative of the actual lifetimes at use conditions. Despite the commercialization of GaN HEMTs for some ground-based applications, mysteries about the device reliability remain [5], as evidenced by the continued research of their life expectancy
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