• Perkins, John D.
• Wagner, J. F.
• Poeppelmeier, K. R.
• Lany, Stephan
• Zunger, Alex
• Zakutayev, Andriy
• Ginley, David S.
• Berry, Joseph J.
• Mason, Thomas O.

Abstract

The microscopic cause of conductivity in transparent conducting oxides like ZnO, In{sub 2}O{sub 3}, and SnO{sub 2} 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 In{sub 2}O{sub 3} samples under high-temperature equilibrium conditions. However, nominally undoped thin-films of In{sub 2}O{sub 3} can exhibit surprisingly high conductivities exceeding by 4-5 orders of magnitude that of bulk samples under identical conditions (temperature and O{sub 2} partial pressure). Employing surface calculations and thickness-dependent Hall measurements, we demonstrate that surface donors rather than bulk defects dominate the conductivity of In{sub 2}O{sub 3} thin films.

Topics

• impedance spectroscopy
• surface
• theory
• thin film
• Hydrogen
• point defect