Figure 1

(a) Photoemission spectra of ${\mathrm{In}}_2{\mathrm{O}}_3(111)$ and ITO(111) excited at 19 eV photon energy. The positions of the valence band onsets (VBO) derived by linear extrapolation of the band edges are indicated. (b) Expanded view of gap states (GS) and CB states close to the Fermi energy. (c) Spectra of the gap state and accumulation layer electrons for ${\mathrm{In}}_2{\mathrm{O}}_3(111)$ excited at 7–9 eV photon energy. Collection angle is $\pm 7°$ in (a)–(c). (d) Spectra of nominally undoped ${\mathrm{In}}_2{\mathrm{O}}_3(111)$ excited at $h\nu =21.2\mathrm{eV}$. Measurements performed after surface preparation by ion bombardment and UHV annealing and then after annealing in oxygen ($1\times {10}^{-6}\mathrm{mbar}$) for 30 min at $600°\mathrm{C}$.Reuse & Permissions

Figure 2

(a) ARPES photocurrent map of conduction band states of ${\mathrm{In}}_2{\mathrm{O}}_3(111)$ excited with 9 eV photons, showing two subbands below the Fermi level. The horizontal axis is the momentum ($k_{\parallel }$) parallel to the surface along $[1\overline{1}0]$, while the vertical axis is the binding energy. The solid curves indicate the positions of two subbands derived from Poisson-Schrödinger calculations. (b) A second-derivative image of the data shown in (a). (c) Momentum distribution curve obtained by summing intensities over a range $\pm 25\mathrm{meV}$ with respect to the Fermi level. The points where the subbands cross the Fermi level are indicated. (d) Downward band bending of 1.30 eV in the CB (upper curve) and 0.45 eV in the VB (lower curve) and corresponding quantized 2D states. The inset shows the near-surface carrier density obtained from Poisson-MTFA calculations. The upper and lower curves correspond to band bending of the CB by 1.30 and 0.45 eV, respectively, yielding surface carrier densities of $5.05\times {10}^{13}{\mathrm{cm}}^{-2}$ and $1.41\times {10}^{13}{\mathrm{cm}}^{-2}$.Reuse & Permissions