Measurement of temperature in active high-power AlGaN/GaN HFETs using Raman spectroscopy

We report on the noninvasive measurement of temperature, i.e., self-heating effects, in active AlGaN/GaN HFETs grown on sapphire and SiC substrates. Micro-Raman spectroscopy was used to produce temperature maps with approximate to1 mum spatial resolution and a temperature accuracy of better than 10 degreesC. Significant temperature rises up to 180 degreesC were measured in the device gate-drain opening. Results from a three-dimensional (3-D) heat dissipation model are in reasonably good agreement with the experimental data. Comparison of devices fabricated on sapphire and SiC substrates indicated that the SiC substrate devices had similar to5 times lower thermal resistance.