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Relationship between non‐localized tail states and carrier transport in amorphous oxide semiconductor, In–Ga–Zn–O
Author(s) -
Nomura K.,
Kamiya T.,
Ohta H.,
Shimizu K.,
Hirano M.,
Hosono H.
Publication year - 2008
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.200778936
Subject(s) - amorphous solid , materials science , annealing (glass) , crystallization , relaxation (psychology) , hall effect , semiconductor , condensed matter physics , electron mobility , oxide , amorphous semiconductors , analytical chemistry (journal) , chemistry , electrical resistivity and conductivity , crystallography , optoelectronics , physics , metallurgy , psychology , social psychology , organic chemistry , chromatography , quantum mechanics
The relationship between non‐localized tail states and carrier transport in transparent amorphous oxide semiconductor, In–Ga–Zn–O (a‐IGZO), was investigated. It was found that the energy width ( E 0 ) of the non‐localized tail states varied from <7 meV to 20 meV depending on the film deposition conditions (i.e. film quality). At carrier concentrations of ∼10 19 cm –3 , Hall mobilities larger than 10 cm 2 (V s) –1 were obtained for the high‐quality films, while they were only several cm 2 (V s) –1 for low‐quality films that have large E 0 values ∼20 meV. However, even for low‐quality films, the E 0 value decreased from 20 meV to 7 meV and their Hall mobilities were increased from ∼1 cm 2 to >10 cm 2 (V s) –1 by post thermal annealing at ≥300 °C. These observations indicate that structural relaxation associated with electron transport starts from ∼300 °C, which is much lower than the crystallization temperature (∼520 °C). This situation is similar to the case of amorphous metals. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)