Understanding Temperature Dependence of ESD Reliability in AlGaN/GaN HEMTs

In this work we report the role of temperature on the ESD reliability of AlGaN/GaN HEMTs, which has not been studied before. We compared two stacks with different buffer thickness and carbon doping concentration, stack 1 (thin buffer and low carbon doping) and stack 2 (thicker buffer and high carbon doping). The trigger voltage (V
tr
) was seen to decrease with increasing temperature in stack 1, while as V
tr
remained independent of the temperature for stack 2. In case of the stack 1, no soft degradation was observed, while as in stack 2 soft degradation leading to high gate leakage was observed at 60 and 100 degree Celsius. The modulation of field due to the temperature is seen to govern the ESD behavior of the stack 1. While as in stack 2, hot holes due to avalanche and hole emission in the high carbon doped buffer determine the breakdown behavior. This study shows the need of an optimum buffer to ensure the ESD robustness of AlGaN/GaN HEMTs with temperature.