Thermal conductivity of GaN crystals in 4.2-300 K range

Results of measurements of thermal conductivity of bulk GaN crystals in the temperature interval 4.2-300 K are reported. Experiments were performed on two types of single GaN crystals grown under high-pressure: highly conducting n-type sample and on a highly resistive sample compensated by magnesium doping. For n-GaN crystals, the highest thermal conductivity kappa(max) is equal to 1600 W/m K at T-max = 45 K, and kappa similar or equal to 220 W/m K at 300 K. Our analysis indicates that for the best n-GaN crystal and for T greater than or equal to T-max, the contribution of Umklapp phonon scattering processes dominate whereas for other samples scattering of phonons by point mass defects represents the main contribution. The dependence of kappa(T) is used to reveal possible mechanisms of thermal resistance of GaN crystals at temperatures T-max. Our thermal conductivity measurements yields Debye's temperature theta(D) approximate to 400 K. (C) 2003 Elsevier Ltd. All rights reserved.