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Enhanced Electron Mobility Due to Dopant‐Defect Pairing in Conductive ZnMgO
Author(s) -
Ke Yi,
Lany Stephan,
Berry Joseph J.,
Perkins John D.,
Parilla Philip A.,
Zakutayev Andriy,
Ohno Tim,
O'Hayre Ryan,
Ginley David S.
Publication year - 2014
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201303204
Subject(s) - materials science , dopant , doping , acceptor , ionized impurity scattering , conductivity , band gap , scattering , impurity , electron mobility , fermi level , transparent conducting film , condensed matter physics , heterojunction , analytical chemistry (journal) , optoelectronics , electron , nanotechnology , thin film , chemistry , optics , physics , organic chemistry , quantum mechanics , chromatography
The increase of the band gap in Zn 1‐ x Mg x O alloys with added Mg facilitates tunable control of the conduction band alignment and the Fermi‐level position in oxide‐heterostructures. However, the maximal conductivity achievable by doping decreases considerably at higher Mg compositions, which limits practical application as a wide‐gap transparent conductive oxide. In this work, first‐principles calculations and material synthesis and characterization are combined to show that the leading cause of the conductivity decrease is the increased formation of acceptor‐like compensating intrinsic defects, such as zinc vacancies ( V Zn ), which reduce the free electron concentration and decrease the mobility through ionized impurity scattering. Following the expectation that non‐equilibrium deposition techniques should create a more random distribution of oppositely charged dopants and defects compared to the thermodynamic limit, the paring between dopant Ga Zn and intrinsic defects V Zn is studied as a means to reduce the ionized impurity scattering. Indeed, the post‐deposition annealing of Ga‐doped Zn 0.7 Mg 0.3 O films grown by pulsed laser deposition increases the mobility by 50% resulting in a conductivity as high as σ = 475 S cm ‐1 .