Thermal and thermoelectric properties of III-nitride and III-oxynitride films

With the aim of fabricating a thermoelectric power device using III-nitrides (Al_1-xIn_xN, InN and AlN) and III-oxynitrides (Al_1-xIn_xO_yN_z and InO_yN_z), we studied their thermal and thermoelectric properties and, in particular, we have focused on their thermal conductivity. Al_1-xIn_xN and Al_1-xIn_xO_yN_z were prepared by reactive radiofrequency sputtering method. We measured the thermal diffusivity and specific heat using the ac calorimetric method, and we estimated values of the thermal conductivity to be 1.5 W/mK (at 673 K) for Al_1-xIn_xN and 0.8 W/mK (at 673 K) for Al_1-xIn_xO_yN_z. These values are much smaller than expected considering the large thermal conductivity of nitrides.