Epitaxial Growth of Complex Metal Oxides

14.5. Epitaxial thermoelectric cobaltate heterostructures

14.5.1. Structural engineering of thermoelectric cobaltate thin films

To enable structural engineering of the Na_xCoO₂ thin films, various single-crystal substrates have been used with a large variation in lattice parameters of their corresponding crystal structures (Brinks, Kuiper, et al., 2014). All substrates have been annealed to form low roughness surfaces with step-terrace structures exhibiting unit-cell-height steps, as determined by AFM. Al₂O₃, MgO and (LaAlO₃)_0.3(Sr₂AlTaO₆)_0.7 (LSAT) were annealed at a temperature of 1050 °C for 1, 2 and 10 h, respectively. LaAlO₃, NdGaO₃, SrTiO₃ and DyScO₃ were annealed at a temperature of 950 °C for 1, 2, 2 and 4 h, respectively, and KTaO₃ was ...