The valence and core levels of ${\text{In}}_2{\text{O}}_3$ and Sn-doped ${\text{In}}_2{\text{O}}_3$ have been studied by hard x-ray photoemission spectroscopy $\left(\text{h}\nu =6000\text{eV}\right)$ and by conventional $\text{Al}\text{K}\alpha$ $\left(\text{h}\nu =1486.6\text{eV}\right)$ x-ray photoemission spectroscopy. The experimental spectra are compared with density-functional theory calculations. It is shown that structure deriving from electronic levels with significant In or Sn $5s$ character is selectively enhanced under 6000 eV excitation. This allows us to infer that conduction band states in Sn-doped samples and states at the bottom of the valence band both contain a pronounced In $5s$ contribution. The In $3d$ core line measured at $\text{h}\nu =1486.6\text{eV}$ for both undoped and Sn-doped ${\text{In}}_2{\text{O}}_3$ display an asymmetric lineshape, and may be fitted with two components associated with screened and unscreened final states. The In $3d$ core line spectra excited at $\text{h}\nu =6000\text{eV}$ for the Sn-doped samples display pronounced shoulders and demand a fit with two components. The In $3d$ core line spectrum for the undoped sample can also be fitted with two components, although the relative intensity of the component associated with the screened final state is low, compared to excitation at 1486.6 eV. These results are consistent with a high concentration of carriers confined close to the surface of nominally undoped ${\text{In}}_2{\text{O}}_3$. This conclusion is in accord with the fact that a conduction band feature observed for undoped ${\text{In}}_2{\text{O}}_3$ in $\text{Al}\text{K}\alpha$ x-ray photoemission is much weaker than expected in hard x-ray photoemission.

• Received 10 December 2009

DOI:https://doi.org/10.1103/PhysRevB.81.165207