Thermoelectric propertiesand thermal diffusivity of III-nitrides and III-oxynitrides thin films preparedby reactive radio-frequency sputtering


R. Izaki1, K. Taki1,K. Yamagiwa1, Y. Iwamura1,2, S. Yamaguchi1,2,A. Yamamoto2


1 Department of Electrical,Electronic and Information Engineering, Kanagawa University, 3-27-1,Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan

2 Energy ElectronicsInstitute, National Institute of Advanced Industrial Science and Technology,AIST, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba 305-8568, Japan


With the aim of fabricating athermoelectric power device using III-nitrides and III-oxynitrides, we recentlystudied, for the first time, their thermoelectric properties and thermaldiffusivity. The samples were Al1-xInxN, InN, and AlN ofIII-nitrides, and Al1-xInxOsNt andInOsNt of III-oxynitrides. They were thin films (~ 0.4 mm) and were prepared by reactiveradio-frequency sputtering on a SiO2 glass substrate at 100oCusing N2 and Ar gases. Through the study of the thermoelectricproperties of the samples, in the case of Al1-xInxN, themaximum power factor was 3.63 x 10-4 W/mK2 at 873K, for Al1-xInxOsNt,the maximum value of power factor was 3.24 x 10-4 W/mK2 at973K, and for InOsNt, the maximum power factor was 3.75x 10-4W/mK2 at 973K. On the other hand, using an ac calorimetric method,we obtained the values of the in-plane thermal diffusivity of our samples ofself-standing (~10mm). The III-nitrides films hada minimum value of 3.14 x 10-6 m2/s for AlN, 7.65 x 10-7 m2/sfor InN, and 7.03 x10-7 m2/s for Al1-xInxN, and theIII-oxynitrides films had a minimum value of 8.02 x 10-7 m2/sfor Al1-xInxOsNt and 8.10x10-7 m2/sfor InOsNt. Those values are much smaller than expectedconsidering the large thermal conductivity of nitrides of single crystal.