Ta-doped SrTiO_3 epitaxial thin film: A promising perovskite for optoelectronics

摘要

SrTiO_3 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 epitaxi-ally stabilized 5 at. % Ta-doped SrTiO_3 (001) thin films on LaAlO_3 (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 SrTiO_3 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 SrTiO_3 films offer it as an exciting material for next generation transparent optoelectronics.