Perovskite ternary oxide materials are promising for use as transparent semiconducting oxides that exhibit high electron mobilities. In order to study the electrical properties of these materials it is necessary to grow single crystal epitaxial films with low defect concentrations. Molecular beam epitaxy (MBE) is a commonly used method to deposit high quality epitaxial films. Incorporation of tin into MBE-grown perovskite films such as BaSnO3 is difficult using elemental sources of tin. Hybrid MBE, in which the elemental source for tin has been replaced with a molecular source, successfully yields stoichiometric BaSnO3. Despite deposition temperatures exceeding 700°C, the structure of the molecular precursor appears to be important. Use of hexamethylditin (HMDT) as the tin source yields phase pure stoichiometric perovskite films while tetraethyltin (TET) yielded tin deficient BaSnO3. In this presentation, we report the use of computational methods to determine gas phase thermochemical properties to predict differences in reactivity of these precursors. Thermochemical properties of the initial precursors as well as a large sample of species resulting from the thermochemical decomposition of these precursors are calculated using the W1-F12 method. These thermochemical properties are used in gas phase equilibrium calculations involving each species and its potential decomposition products. The results of these calculations will be used to inform further calculations involving the most stable intermediates in surface reactions.

Composite thermochemical approach to tin alkyl precursors in hybrid molecular beam epitaxy

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.