A Very Robust AlGaN/GaN HEMT Technology to High Forward Gate Bias and Current

Bradley D Christiansen,Ramakrishna Vetury,Ronald A Coutu,Eric R Heller,Jeffrey B Shealy

doi:10.1155/2012/493239

Bradley D Christiansen, Ramakrishna Vetury + Show 3 more

Open Access

https://doi.org/10.1155/2012/493239

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Abstract

Reports to date of GaN HEMTs subjected to forward gate bias stress include varied extents of degradation. We report an extremely robust GaN HEMT technology that survived—contrary to conventional wisdom—high forward gate bias (+6 V) and current (>1.8 A/mm) for >17.5 hours exhibiting only a slight change in gate diode characteristic, little decrease in maximum drain current, with only a 0.1 V positive threshold voltage shift, and, remarkably, a persisting breakdown voltage exceeding 200 V.

Highlights

There are recent reports stating that high negative gate bias causes the gates of GaN HEMTs to degrade
Other reports state that forward gate current limits the survival times of GaN HEMTs, especially during RF operation [4, 5]
Reference [7] considered the effects of high positive gate bias on GaN HEMTs with gateintegrated field plates, Lg = 0.25 μm, and Wg = 2 × 25 μm

Summary

Introduction

There are recent reports stating that high negative gate bias causes the gates of GaN HEMTs to degrade. The signature of this degradation mechanism is an increase in gate leakage current [1,2,3]. Other reports state that forward gate current limits the survival times of GaN HEMTs, especially during RF operation [4, 5]. Despite the extremely high biases, the devices we tested survived well past the current density in [6] and were less conductive and with less VGon degradation than those in [7]. It is noted that the devices we tested survived the stresses—contrary to conventional wisdom—with very little degradation in device drain current and voltage capability

Experimental

Results and Discussion

Conclusion