Electrothermal Mapping of AlGaN/GaN HEMTs Using Microresistance Thermometer Detectors

Self-heating effects in AlGaN/GaN high-electron mobility transistors (HEMTs) can notably reduce electron mobility and produce reliability concerns. Electrothermal characterization and appropriate thermal management are required to address this situation. This letter presents the measurement of channel temperature (T_ch) of GaN HEMTs in multiple bias conditions with a good accuracy. The measurements are executed using the integrated microresistance thermometer detector (μRTD) technique in AlGaN/GaN HEMTs on SiC and sapphire substrates. The integrated Ti/Pt μRTD sensor with linear resistance-temperature characteristic is used to obtain an I_ds-V_ds-T_ch map for each device. Thermal resistances are compared for similar operation conditions, obtaining RTH = 34.7 °C · W^-1 for the HEMT on SiC and RTH = 157.2 °C · W^-1 for the HEMT on sapphire.