It was found experimentally, by using the 3-omega technique, that the thermal conductivity of GaN depended critically upon the dislocation density. For GaN with dislocation densities lower than 106/cm2, the thermal conductivity was independent of dislocation density. The thermal conductivity decreased, with a logarithmic dependence, for material with dislocation densities ranging from 107 to 1010/cm2. These results were in agreement with theoretical predictions. The study indicated that the hydride vapor phase epitaxy method offered an attractive route for the formation of semi-insulating GaN with optimum thermal conductivity values of around 230W/mK, and a very low dislocation density of near to 5 x 104/cm2.

Accurate Dependence of Gallium Nitride Thermal Conductivity on Dislocation Density. C.Mion, J.F.Muth, E.A.Preble, D.Hanser: Applied Physics Letters, 2006, 89[9], 092123 (3pp)