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Surface Origin of High Conductivities in Undoped In_{2}O_{3} Thin Films

TitleSurface Origin of High Conductivities in Undoped In_{2}O_{3} Thin Films
Publication TypeJournal Article
Year of Publication2012
AuthorsLany, S., A. Zakutayev, T. Mason, J. F. Wager, K. Poeppelmeier, J. Perkins, J. Berry, D. Ginley, and A. Zunger
JournalPhysical Review Letters
Start Page016802
Date Published01/2012

The microscopic cause of conductivity in transparent conducting oxides like ZnO, In₂O₃, and SnO₂ is generally considered to be a point defect mechanism in the bulk, involving intrinsic lattice defects, extrinsic dopants, or unintentional impurities like hydrogen. We confirm here that the defect theory for O-vacancies can quantitatively account for the rather moderate conductivity and off-stoichiometry observed in bulk In₂O₃ samples under high-temperature equilibrium conditions. However, nominally undoped thin-films of In₂O₃ can exhibit surprisingly high conductivities exceeding by 4–5 orders of magnitude that of bulk samples under identical conditions (temperature and O₂ partial pressure). Employing surface calculations and thickness-dependent Hall measurements, we demonstrate that surface donors rather than bulk defects dominate the conductivity of In₂O₃ thin films.

Short TitlePhys. Rev. Lett.