A set of LaAlO${}_3$/SrTiO${}_3$ (LAO-STO) interfaces has been probed by x-ray photoemission spectroscopy in order to contrast and compare the effects of LAO overlayer thickness and of the growth conditions on the electronic properties of these heterostructures. These effects are tracked by considering the band offset and the density of Ti${}^{+3}$ states, respectively. It is shown that the dominant effects on the local electronic properties are determined by the O${}_2$ partial pressure during the growth. In particular, a low $P_{{\text{O}}_2}$ yields Ti${}^{+3}$ states with higher density and lower binding energy compared to the sample grown at high $P_{{\text{O}}_2}$ or to the bare STO reference sample. Band-offset effects are all below about 0.7 eV, but a careful analysis of Ti $2p$ and Sr $3d$ peaks shows that valence-band offsets can be at the origin of the observed peak width. In particular, the largest offset is shown by the conducting sample, which displays the largest Ti $2p$ and Sr $3d$ peak widths.

• Received 7 August 2012

DOI:https://doi.org/10.1103/PhysRevB.87.075435