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Deep subgap feature in amorphous indium gallium zinc oxide: Evidence against reduced indium (Phys. Status Solidi A 7∕2015)
Author(s) -
Sallis Shawn,
Quackenbush Nicholas F.,
Williams Deborah S.,
Senger Mikell,
Woicik Joseph C.,
White Bruce E.,
Piper Louis F. J.
Publication year - 2015
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201570443
Subject(s) - indium , amorphous solid , opacity , gallium , valence (chemistry) , oxide , materials science , crystallite , condensed matter physics , chemistry , optoelectronics , physics , crystallography , metallurgy , optics , quantum mechanics
Amorphous indium gallium zinc oxide (a‐IGZO) has shown promise as the active layer of transparent thin film transistors (TTFTs). Within a‐IGZO films, disorder‐induced subgap states can form that both reduce the optical transparency and performance of the TTFTs. Sallis et al. (pp. 1471–1475 ) report their spectroscopic and microscopic studies of a‐IGZO films with and without subgap features to determine the microscopic origin of the subgap states. Their work rules out reduced indium species contributing the deep subgap states lying near the valence band edge. Instead, reduced indium states contribute near the conduction band edge. Their experimental results confirm atomistic calculations that under‐coordinated oxygen is responsible for the deep subgap states and that under‐coordinated indium (including metallic nano‐crystallites) forms the shallow subgap states. The cover image displays transparent and opaque a‐IGZO samples. The opaque films are shown to have greater variation in their local atomic arrangements, i.e. more under‐coordinated oxygen and indium. This artwork was developed as part of a Graphic Design in Physics project at Binghamton University. Sallis et al. thank Matthew Wahila and Annie Dailey for their artwork.