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Suppression of Grain Boundary Scattering in Multifunctional p‐Type Transparent γ‐CuI Thin Films due to Interface Tunneling Currents
Author(s) -
Kneiß Max,
Yang Chang,
BarzolaQuiquia José,
Benndorf Gabriele,
von Wenckstern Holger,
Esquinazi Pablo,
Lorenz Michael,
Grundmann Marius
Publication year - 2018
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201701411
Subject(s) - grain boundary , materials science , quantum tunnelling , condensed matter physics , magnetoresistance , thin film , scattering , weak localization , electrical resistivity and conductivity , carrier scattering , magnetic field , optoelectronics , nanotechnology , optics , composite material , microstructure , electrical engineering , engineering , physics , quantum mechanics
Transparent p‐type conductive γ‐CuI thin films typically exhibit unexpectedly high hole mobilities in the range of 10 cm 2 V −1 s −1 even when heavily textured. To explain this phenomenon, the transport properties of such thin films are investigated. The temperature‐dependent resistivities of the textured (111)‐oriented films with different carrier concentration are fitted using the fluctuation‐induced tunneling conductivity (FITC) model in series with a power law. The FITC model describes barriers at the grain boundaries whereas the power law considers the scattering in the metallic interior of the grains. Magnetoresistance measurements performed on a reactively DC‐sputtered thin film at low temperatures ( T < 8 K) suggest a 2D weak antilocalization effect with phase coherence lengths of about 50 nm. This is corroborated by a typical logarithmic temperature dependence of the zero‐field conductance. An n‐type inversion layer or a defect band at the interfaces of the grains as origin of the 2D carrier system and the barriers at the grain boundaries is proposed. This leads to a conclusive description of the electrical transport properties of γ‐CuI thin films and explains the high hole mobilities which are due to a suppressed backscattering at the grain boundaries in the presence of tunneling channels.