Thermal Conductivity of Amorphous Indium-Gallium-Zinc Oxide Thin Films

We investigated the thermal conductivity of 200-nm-thick amorphous indium-gallium-zinc-oxide (a-IGZO) films. Films with a chemical composition of In : Ga : Zn = 1 : 1 : 0.6 were prepared by dc magnetron sputtering using an IGZO ceramic target and an Ar-O-2 sputtering gas. The carrier density of the films was systematically controlled from 10(14) to > 10(19) cm(-3) by varying the O-2 flow ratio. Their Hall mobility was slightly higher than 10 cm(2) .V-1 .s(-1). Those films were sandwiched between 100-nm-thick Mo layers; their thermal diffusivity, measured by a pulsed light heating thermoreflectance technique, was similar to 5.4 x 10(-7) m(2) .s(-1) and was almost independent of the carrier density. The average thermal conductivity was 1.4W.m(-1) .K-1. (C) 2013 The Japan Society of Applied Physics