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Origin of channel/dielectric interfacial trap states modification by ultraviolet irradiation on organic thin‐film transistors
Author(s) -
Lee Kimoon,
Im Seongil
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.201431457
Subject(s) - pentacene , materials science , thin film transistor , irradiation , gate dielectric , threshold voltage , dielectric , optoelectronics , ultraviolet , ultraviolet photoelectron spectroscopy , dipole , transistor , voltage , layer (electronics) , condensed matter physics , nanotechnology , chemistry , electronic structure , electrical engineering , physics , engineering , organic chemistry , nuclear physics
The authors report on the origin of channel/dielectric interfacial states modified by ultraviolet (UV) irradiation on pentacene thin‐film transistors (TFTs) with poly‐4‐vinylphenol and AlO x double gate dielectric. Exposing the device to 352 nm UV irradiation on caused a positive threshold voltage ( V th ) shift, and then photo‐excited charge‐collection spectroscopy (PECCS) was applied to the device to clarify the changes of the interfacial density of states (DOS) as the origin of V th modification. From the PECCS measurement, it could be probed that there was a drastic decrease in DOS for deep traps at ∼1.31 and ∼1.38 eV above the highest occupied molecular orbital level of pentacene. Consequently, we can conclude that the positive shift of V th for pentacene‐TFT by UV irradiation results from the elimination of deep hole traps, which could be introduced by the interfacial dipoles at the channel/dielectric interface.