On the upper limit of thermal conductivity GaN crystals

TL;DR

This paper estimates the maximum thermal conductivity of perfect GaN crystals, providing an upper limit that refines previous calculations and extends temperature dependence models.

Contribution

It presents a new upper limit estimate for GaN crystal thermal conductivity and extends the temperature dependence model to lower temperatures.

Findings

Maximum thermal conductivity estimated at 4800 W/Km at 32 K.

Extended the ppa ependence to 200-300 K.

Fitted experimental data to Callaway's formula with =1.35.

Abstract

The maximal value of thermal conductivity \kappa_{max} of the perfect wurzite GaN crystal containing isotopes of natural abundance is estimated. Our upper limit of \kappa=4800 W/Km at T_{max}=32 K is smaller than calculated by Liu and Balandin \kappa=6000 W/Km and higher than obtained by Slack et al \kappa=3750 W/Km. The phenomenological dependence \kappa \propto T^{-1.43} obtained by Mion et al for the temperature interval 300-450 K is extended to 200-300K. 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 \gamma = 1.35.