MOCVD 법에 의한 Bi-Te계 열전소재 제조 및 박막형 열전소자 제작

Abstract

Bismuth-telluride based thin film materials are grown by Metal Organic Chemical Vapor Deposition(MOCVD). A planar type thermoelectric device has been fabricated using p-type <TEX>$Bi_{0.4}Sb_{1.6}Te_3$</TEX> and n-type <TEX>$Bi_2Te_3$</TEX> thin films. Firstly, the p-type thermoelectric element was patterned after growth of <TEX>$4{\mu}m$</TEX> thickness of <TEX>$Bi_{0.4}Sb_{1.6}Te_3$</TEX> layer. Again n-type <TEX>$Bi_2Te_3$</TEX> film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for <TEX>$Bi_2Te_3$</TEX>. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the sample was heated by heating block and the voltage output measured. As expected for a thermoelectric generator, the voltage decreases linearly, while the power output rises to a maximum. The highest estimated power of <TEX>$1.3{\mu}W$</TEX> is obtained for the temperature difference of 45 K. we provide a promising procedure for fabricating thin film thermoelectric generators by using MOCVD grown thermoelectric materials which may have nanostructure with high thermoelectric properties.