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AlGaN/GaN heterostructure field effect transistors with a 150 nm thick GaN channel within stacked Al xGa1−xN layers were investigated using Raman thermography. By fitting a thermal simulation to the measured temperatures, the thermal conductivity of the GaN channel was determined to be 60 W m−1 K−1, over 50% less than typical GaN epilayers, causing an increased peak channel temperature. This agrees with a nanoscale model. A low thermal conductivity AlGaN buffer means the GaN spreads heat; its properties are important for device thermal characteristics. When designing power devices with thin GaN layers, as well as electrical considerations, the reduced channel thermal conductivity must be considered.
Hodges, C., Anaya Calvo, J., Stoffels, S., Marcon, D., & Kuball, M. (2013). AlGaN/GaN field effect transistors for power electronics: Effect of finite GaN layer thickness on thermal characteristics. Applied Physics Letters, 103(20), . https://doi.org/10.1063/1.4831688