Temperature dependence of thermal conductivity of AlxGa1-xN thin films measured by the differential 3ω technique

Reliable values of thermal conductivity of thin films made of GaN and its alloys are important for further development of nitride technology due to the problem of self-heating in GaN-based power transistors and optical devices. Using the differential 3omega technique we measured the thermal conductivity of AlxGa1-xN thin films (x=0 and 0.4) grown by the hydride vapor phase epitaxy. Thermal conductivity of the examined Al0.4Ga0.6N alloy, which is about 25 W/mK at 300 K, displays a rather unusual temperature dependence. A noticeable growth of the thermal conductivity with temperature up to 350 K is more characteristic for amorphous or completely disordered materials. The measured high-temperature thermal conductivity data are in good agreement with predictions based on the virtual crystal model. Obtained results are important for modeling the self-heating effects in GaN transistors and can be used for the device structure optimization. (C) 2004 American Institute of Physics.