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On the modulation of oxygen sensitivity of In 2 O 3 thin films: effects of moisture and dc bias
Author(s) -
Zhu Yihao,
Koley Goutam
Publication year - 2014
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.201431281
Subject(s) - materials science , adsorption , sensitivity (control systems) , dc bias , moisture , oxygen , analytical chemistry (journal) , gating , thin film , biasing , ion , molecule , conductivity , optoelectronics , chemistry , nanotechnology , voltage , composite material , electrical engineering , electronic engineering , environmental chemistry , physiology , organic chemistry , engineering , biology
Oxygen sensing characteristics of In 2 O 3 thin film at room temperature have been investigated through conductivity measurements using interdigitated metal finger patterned devices. We observed that the O 2 sensitivity gets affected very significantly in presence of moisture, as well as with applied dc bias. The O 2 sensitivity was found to increase several times in moist ambient compared to dry ambient condition. Higher dc bias also dramatically improved the sensitivity, which varied more than two orders of magnitude as the dc bias was increased from 0.5 to 10 V. We propose that the observed increase in sensitivity in presence of moisture is caused by enhanced surface electron density on In 2 O 3 thin film resulting from the donation of electrons caused by the chemisorbed water molecules. The adsorption of O 2 molecules, which subsequently formed O 2 − ions, leads to chemical gating of the sensor devices, which under larger dc bias produced a higher fractional change in current leading to higher sensitivity.