  Complex oxide perovskites have been widely studied for their diverse
functional properties. When dimensionally reduced to epitaxial thin films and
heterostructures these properties are frequently tunable, and the
symmetry-breaking inherent to thin film structures can result in the emergence
of new, novel, phenomena and properties. However, the ability to control and
harness these structures relies on an atomic-level understanding and control of
the growth process, made challenging by the lack of suitable in situ
compositional characterization tools. In this work, the
compositional-dependence of SrTiO3 on pulsed laser deposition growth parameters
is investigated with in situ Auger electron spectroscopy and ex situ thin film
x-ray diffraction, and verified with a simple escape depth model. We show that
this is a suitable technique for monitoring subtle compositional shifts
occurring during the deposition process, with broad implications for the
continued development of thin film synthesis techniques.
