On the upper limit of thermal conductivity GaN crystals

The maximal value of thermal conductivity κ max of the perfect wurtzite GaN crystal containing isotopes of natural abundance is estimated. Our upper limit of κ = 4800 W/K m at T max = 32 K is smaller than that calculated by Liu and Balandin κ = 6000 W/K m and higher than that obtained by Slack et al. κ = 3750 W/K m . The phenomenological dependence κ ∝ T − 1.43 obtained by Mion et al. for the temperature interval 300–450 K is extended to 200–300 K. For temperatures higher than T max the best fitting of our experimental data to Callaway’s formula is obtained for Grueneisen’s constant equal to γ = 1.35 .