Small signal model parameters analysis of GaN and GaAs based HEMTs over temperature for microwave applications

• Thermal and small signal model parameters for two different technologies: gallium nitride (GaN) and gallium arsenide (GaAs) are investigated.
• Temperature coefficients of the small signal model parameters are extracted.
• The trend of intrinsic capacitances with temperature for the GaN and GaAs devices are completely different.
• Thermal behavior of the device parameters demonstrates the great potential of GaN device compared to the matured GaAs technology.
• These results are important for technology of choice for current and future applications.

Thermal and small-signal model parameters analysis have been carried out on 0.5 μm × (2 × 100 μm) AlGaAs/GaAs HEMT grown on semi-insulating GaAs substrate and 0.25 μm × (2 × 100 μm) AlGaN/GaN HEMT grown on SiC substrate. Two different technologies are investigated in order to establish a detailed understanding of their capabilities in terms of frequency and temperature using on-wafer S-parameter measurement over the temperature range from −40 to 150 °C up to 50 GHz. The equivalent circuit parameters as well as their temperature-dependent behavior of the two technologies were analyzed and discussed for the first time. The principle elevation or degradation of transistor parameters with temperature demonstrates the great potential of GaN device for high frequency and high temperature applications. The result provides some valuable insights for future design optimizations of advanced GaN and a comparison of this with the GaAs technology.