Resistive Nickel Temperature Sensor Integrated Into Short-Gate Length AlGaN/GaN HEMT Dedicated to RF Applications

This letter describes a new method to extract the operating temperature in short-gate length AlGaN/GaN high electron mobility transistors (HEMTs) dedicated to RF applications. For this goal, a nickel resistive sensor is integrated into the HEMT active area close to the hot thermal spot thanks to a well-suited technological process. Operating temperature of the HEMT is extracted showing the capabilities of this method to monitor the thermal behavior of the device. Furthermore, it is shown that dc and RF characteristics are not degraded by additional parasitic capacitance and/or sensor biasing.

I. Introduction

Gallium Nitride (GaN) properties are attractive to RF and power applications. Outstanding GaN properties (high gap energy, high breakdown voltage, high electron saturation velocity) enable to fabricate High Electron Mobility Transistors (HEMTs) with high performance in terms of current density, operating voltage and frequency [1]. However, self-heating leads to harmful consequence on performance and reliability. Extracting accurately temperature of operating device is then important to model its electrical behavior. Moreover, monitoring device temperature under test will permit to predict its lifetime in real time.