Measuring the thermal conductivity of the GaN buffer layer in AlGaN/GaN HEMTs

Abstract

The thermal conductivity of the GaN buffer layer in AlGaN/GaN devices can be determined by measuring the vertical temperature gradient through this layer. In this work, diamond micro-thermometers and standard micro-Raman thermography were used to determine the surface and volumetric depth average temperature, respectively, of the carbon-doped GaN buffer layer in AlGaN/GaN transistors. By comparing measured temperatures with finite element thermal simulation, a thermal conductivity of 200 ± 20 Wm−1 K−1 was obtained for a carbon-doped GaN layer with a doping concentration of 1017 cm−3.