A study of temperature field in a GaN heterostructure field-effect transistor

We propose in this paper a three-dimensional finite element based heat transfer model for a Gallium Nitride-based Heterostructure Field-Effect Transistor (henceforth referred to as GaN HFET). Analyses were carried out to study the distribution of temperature in the HFET under steady state conditions for two different steady-current inputs. Two different substrates for the HFET, sapphire and silicon carbide (SiC), were studied. The paper discusses the effect of using a heat sink and also that of using reasonable contact resistances on the substrate side of the HFET, on the temperature profile. In all cases, the gate region of the HFET was found to attain the highest temperature. Subsequent experiments to validate the results of the computational analysis were carried out at the Oakridge National Laboratories, Knoxville, and are also presented in this paper.