Time resolved temperature profiles of high power HEMTs by photocurrent spectral analysis

We report of time-resolved photocurrent thermography to measure transient temperatures in semi-conductor devices with micrometer spatial resolution. This new technique is illustrated both for AlGaN/GaN and AlGaAs/GaAs HEMTs. A temporal resolution of microsecond order is demonstrated. The advantage of this method consists in the capability of measuring directly the temperature of the HEMT channel, even if this is well below the surface due to the fact that the collection efficiency of the channel is much higher.