Secondary ion mass spectroscopy (SIMS) was used to investigate carbon impurity concentrations in stoichiometric SrTiO3 films grown by a hybrid molecular beam epitaxy approach that uses an effusion cell to supply strontium, a rf plasma source for oxygen and a metal organic titanium source (titanium tetra isopropoxide). The carbon concentration in the films was measured as a function of growth parameters. At sufficiently high growth temperatures (>800 °C), the films contain a few ppm of carbon. The challenges in accurately quantifying low carbon concentrations are discussed. A carbon-containing contamination layer is detected on the surfaces of SrTiO 3 substrates and air-exposed films by SIMS and in scanning transmission electron microscopy. The contamination layer could be removed by high-temperature predeposition oxygen plasma cleaning.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films|
|State||Published - 2009|
Bibliographical noteFunding Information:
This research was supported by the National Science Foundation through the UCSB MRL (Award No. DMR 05-20415). Acquisition of the oxide MBE system was made possible through a NSF MRI grant (NSF Grant No. DMR-0619698).