Electron transport and thermoelectric response of Nb- or La-doped SrTiO/sub 3/ epitaxial film at high-temperature

Abstract

To clarify the potential of n-type conductive SrTiO/sub 3/ as a high temperature thermoelectric material, carrier concentration dependence of the thermoelectric figure of merit, ZT of SrTiO/sub 3/ at high-temperature (1000 K) is clarified using heavily Nb- or La-doped SrTiO/sub 3/ epitaxial films, which were grown on insulating (100)-oriented LaAlO/sub 3/ single-crystalline substrates by a pulsed-laser deposition method. Carrier concentration, Hall mobility, Seebeck coefficient and thermal conductivity of Nb- or La-doped SrTiO/sub 3/ epitaxial films were experimentally evaluated at 1000 K with an aid of theoretical analysis. The maximum ZT value was obtained ZT = 0.37 for 4 /spl times/ 10/sup 21/ cm/sup -3/ Nb-doped SrTiO/sub 3/ at 1000 K, which is the largest value among n-type oxide semiconductors ever reported.