  LaCrO$_3$ (LCO) / SrTiO$_3$ (STO) heterojunctions are intriguing due to a
polar discontinuity along (001), two distinct and controllable interface
structures [(LaO)$^+$/(TiO$_2$)$^0$ and (SrO)$^0$/(CrO$_2$)$^-$], and
interface-induced polarization. In this study, we have used soft- and hard
x-ray standing-wave excited photoemission spectroscopy (SW-XPS) to generate a
quantitative determination of the elemental depth profiles and interface
properties, band alignments, and the depth distribution of the
interface-induced built-in potentials in the two constituent oxides. We observe
an alternating charged interface configuration: a positively charged
(LaO)$^+$/(TiO$_2$)$^0$ intermediate layer at the
LCO$_\textbf{top}$/STO$_\textbf{bottom}$ interface and a negatively charged
(SrO)$^0$/(CrO$_2$)$^-$ intermediate layer at the
STO$_\textbf{top}$/LCO$_\textbf{bottom}$ interface. Using core-level SW data,
we have determined the depth distribution of species, including through the
interfaces, and these results are in excellent agreement with scanning
transmission electron microscopy and electron energy loss spectroscopy
(STEM-EELS) mapping of local structure and composition. SW-XPS also enabled
deconvolution of the LCO-contributed and STO- contributed
matrix-element-weighted density of states (MEWDOSs) from the valence band (VB)
spectra for the LCO/STO superlattice (SL). Monitoring the VB edges of the
deconvoluted MEWDOS shifts with a change in probing profile, the alternating
charge- induced built-in potentials are observed in both constituent oxides.
Finally, using a two-step simulation approach involving first core-level
binding energy shifts and then valence-band modeling, the built-in potential
gradients across the SL are resolved in detail and represented by the depth
distribution of VB edges.
