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Oxygen vacancies effects in a‐IGZO: Formation mechanisms, hysteresis, and negative bias stress effects (Phys. Status Solidi A 6∕2017)
Author(s) -
de Jamblinne de Meux Albert,
Bhoolokam Ajay,
Pourtois Geoffrey,
Genoe Jan,
Heremans Paul
Publication year - 2017
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.201770131
Subject(s) - materials science , fermi level , condensed matter physics , semiconductor , oxygen , indium , hysteresis , oxide , chemistry , optoelectronics , metallurgy , physics , organic chemistry , quantum mechanics , electron
The amorphous oxide semiconductor Indium‐Gallium‐Zinc‐Oxide (a‐IGZO) has gained a large technological relevance as a semiconductor for thin‐film transistors in active‐matrix displays. Yet, major questions remain unanswered regarding the atomic origin of threshold voltage control, doping level, hysteresis, negative bias stress (NBS), and negative bias illumination stress (NBIS). de Jamblinne de Meux et al. (article No. 201600889 ) have undertaken a systematic study of the effects of oxygen vacancies on the properties of a‐IGZO by relating experimental observations to material insights gained from first‐principle simulations. The cover figure presents different conformations of Metal‐Metal bonds obtained after the removal of an oxygen atom in IGZO for which, the iso‐surface of the electronic wave‐function and its phase are colored in blue and yellow. These Metal‐Metal defects are stable for a fermi‐level deep in the conduction band and spontaneously break up for a fermi‐level close to the valence band. Their transition states can vary upon charge and discharge, resulting in hysteresis of the transfer curve of a‐IGZO devices. Under NBS, the creation of oxygen vacancies becomes energetically very stable, hence thermodynamically very likely to occur. This generation process is correlated with the occurrence of the negative bias stress instabilities observed in a‐IGZO transistors.