The temperature dependence of the thermal conductivity of single crystal GaN films

The thermal conductivity of both LEO and HVPE single crystals of GaN have been measured over the temperature range of 60 K to 300 K using an electrical third harmonic technique. In contrast to the previously reported results of Sichel and Pankove, the thermal conductivity increases with decreasing temperature below room temperature, reaches a maximum and then decreases with further decreases in temperature. The thermal conductivity of the LEO-GaN is higher at all temperatures than the HVPE materials. The higher thermal conductivity is correlated with lower values of the threading dislocation density.