Ta-doped SrTiO3 epitaxial thin film: A promising perovskite for optoelectronics

Abstract

SrTiO3 is a wide bandgap cubic perovskite oxide and displays many exotic properties, i.e., transparent conductivity, photocatalysis, metallicity, ferroelectricity, superconductivity, colossal magnetoresistance, two-dimensional electron gas, etc., due to the manipulations of defect chemistry and constituent elements via impurity doping. This paper reports on the intricacy of the structural and optoelectronic properties of the epitaxially stabilized 5 at. % Ta-doped SrTiO3 (001) thin films on LaAlO3 (001) substrates by systematically varying the growth temperature and oxygen partial pressure during the pulsed laser deposition process. The influences of Ta dopant and growth parameters on the epitaxial quality of these layers are understood by determining the dopant location and its concentration in the SrTiO3 lattice. The complex relationships of optical and electronic properties on growth parameters, dopant concentration, and single crystal quality of the films are demonstrated. The observed low resistivity (∼5 × 10−3 Ω cm) and high optical transparency (∼85%–90%) of optimized Ta-doped SrTiO3 films offer it as an exciting material for next generation transparent optoelectronics.

Potential of La-Doped SrTiO3 Thin Films Grown by Metal–Organic Vapor Phase Epitaxy for Thermoelectric Applications

“…SrTiO 3 is a promising material for thermoelectric applications because it exhibits a large Seebeck coefficient even at high temperatures, − and it is chemically inert and stable up to 1000 °C. Semiconducting n-type doped SrTiO 3 has been achieved by the incorporation of different elements like Nb or Ta on the Ti site or Y, Sm, or La on the Sr site. A weakness of SrTiO 3 regarding its use in thermoelectric devices is the relatively low electrical conductivity, based on the high effective mass and the resulting low charge carrier mobility, and simultaneously high thermal conductivity κ (about 5–18 Wm –1 K –1 ), which is reasoned by the centrosymmetric cubic structure that offers low effective phonon scattering centers.…”