High-resolution Raman temperature measurements in GaAs p-HEMT multifinger devices

Self-heating in multifinger GaAs pseudomorphic-HEMT devices was investigated by micro-Raman spectroscopy. The device temperature was probed on the die as a function of applied bias, external heating, and device geometry. The temperature of the top GaAs layer was recorded inside the source-drain gap, as well as on the device periphery using 488-nm laser excitation. Obtained Raman temperatures were found to be higher than infrared thermography results, which is due to the improved-spatial resolution of micro-Raman spectroscopy. Thermal resistance and crosstalk in the multifinger devices was evaluated as a function of thermal stress and finger pitch.