Analysis of Thermal Characteristics of AlGaN/GaN Heterostructure Field-Effect Transistors Using Micro-Raman Spectroscopy

AbstractWe report on the non-invasive measurement of temperature, i.e., self-heating effects, in active AlGaN/GaN heterostructure field effect transistors (HFETs). Micro-Raman spectroscopy was used to produce temperature maps with ≈1 μm spatial resolution and a temperature accuracy of better than 10°C. Significant self-heating effects in the source-drain opening of AlGaN/GaN HFETs were measured. Devices grown on sapphire and SiC substrates were compared. Three-dimensional finite-difference heat dissipation calculations were performed as function of device geometry.

We have calculated the thermal boundary resistance at the GaN/SiC, GaN/sapphire and GaN/AlN interfaces in the diffuse mismatch approximation. The obtained values were then used to examine the effect of the thermal boundary resistance on heat diffusion in AlGaN/GaN heterostructure field-effect transistors. The results show that the thermal boundary resistance at the device layer interfaces can strongly influence the temperature rise in the device channel.