Publication Type:Conference Paper
Source:2010 14th International Heat Transfer Conference, IHTC 14, Volume 4, p.839-843 (2010)
Keywords:Conduction band edge, Double doping, Heat Transfer, Impurity bands, Lanthanum, Lanthanum alloys, Mass defect, Optical spectroscopic, Oxygen deficient, oxygen vacancies, pulsed laser deposition, SrTiO, Strontium titanates, Theoretical prediction, Thermal conductivity, Thermoelectric material, Thermoelectric performance, Thermoelectric power, Thermoelectric power factors, Thermoelectricity, thin films, Transport measurements
Lanthanum (La) doped Strontium Titanate (SrTiO3) is amongst the most promising n-type thermoelectric materials for power generation. We report a double doping method for thin films of SrTiO3 (STO), grown by Pulsed Laser Deposition (PLD), where doping of STO in the Sr-site by Lanthanum is accompanied by doping with oxygen vacancies. In the past theoretical predictions have shown that introducing oxygen vacancies in STO produces a high-effective mass defect band just below the conduction band edge, explaining the high seebeck coefficient observed in oxygen deficient STO. Based on careful transport measurements, we show that it is possible to obtain enhanced thermoelectric power factor by double doping, using La and oxygen vacancies in these thin films. With the aid of optical spectroscopic measurements, we establish the presence of the impurity band created by the vacancies and validate their role in the enhanced thermoelectric performance with structural and transport measurements. The presence of oxygen vacancies also serves to decrease the thermal conductivity due to effective phonon scattering. © 2010 by ASME.
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