Phonon heat conduction in Al_xGa_1-xN film

Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre For Basic Sciences Block JD, Sector III, Saltlake, Kolkata 700098, India

^a saswati@bose.res.in

Received: 2 December 2011
Accepted: 4 January 2012

Abstract

We report on theoretical investigation of the thermal conductivity of Al_xGa_1−xN (0≤x≤1) films over a wide range of temperature by using both Debye's and Callaway's model. Our calculated results agree well with most of the available experimental results of films grown by Hidride Vapor Phase Epitaxy (HVPE) and Metal Oxide Chemical Vapor Deposition (MOCVD) techniques. We find that the large contribution of alloy mass disorder and point impurity scattering is the primary reason for the increase in thermal conductivity of Al_xGa_1−xN alloy film beyond room temperature. Above room temperature, MOCVD films have lower thermal conductivity compared to HVPE grown films due to the presence of a larger amount of defects in MOCVD films as compared to HVPE films. Variation of thermal resistivity with x in Al_xGa_1−xN shows a peak at x=0.7 due to the highest contribution of mass disorder.