Epitaxial stannate pyrochlore thin films: Limitations of cation stoichiometry and electron doping

We have studied the growth of epitaxial films stannate pyrochlores with a general formula A2Sn2O7 (A = La and Y) find that it is possible to incorporate ∼25% excess A-site constituent; in contrast, any tin expelled. unravel defect chemistry, allowing for incorporation species mechanism behind expulsion. An surplus manifested by shift film diffraction peaks, expulsion apparent from surface morphology film. In an attempt increase La2Sn2O7 conductivity through n-type doping, substantial quantities been substituted antimony while maintaining good quality. The sample remained insulating as explained first-principles computations, showing both oxygen vacancy antimony-on-tin substitutional defects are deep. Similar conclusions drawn on Y2Sn2O7. alternative dopant, fluorine oxygen, shallow according computations more likely lead electrical conductivity. bandgaps stoichiometric Y2Sn2O7 were determined spectroscopic ellipsometry be 4.2 eV 4.48 eV, respectively.