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P‐5.4: Processing Effects on the Performances of Indium Zinc Bismuth Oxide Thin Film Transistors
Author(s) -
Lin Dong,
Zhang Qun
Publication year - 2019
Publication title -
sid symposium digest of technical papers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.351
H-Index - 44
eISSN - 2168-0159
pISSN - 0097-966X
DOI - 10.1002/sdtp.13627
Subject(s) - sputtering , thin film transistor , materials science , sputter deposition , amorphous solid , analytical chemistry (journal) , threshold voltage , optoelectronics , thin film , layer (electronics) , transistor , electrical engineering , nanotechnology , voltage , chemistry , crystallography , engineering , chromatography
Bismuth (Bi) has a stronger bond dissociation energy to the oxygen atom (337.2 kJ mol ‐1 ) than indium (320.1 kJ mol ‐1 ) and zinc (159.0 kJ mol ‐1 ) [1]. Therefore, Bi can serve as a carrier suppressor for indium zinc oxide (IZO). In this work, bottom‐gate amorphous Bi doped IZO thin film transistors (a‐IZBO TFTs) were fabricated by means of radio‐frequency magnetron sputtering. During the deposition, pure Ar gas with a fixed flow rate of 30 sccm was introduced into the chamber and the sputtering pressure was maintained at 0.4 Pa. Effects of experimental variables including channel layer thickness (8, 30 and 38 nm) and sputtering power (30, 50, 70 and 90 W) on the performances of a‐IZBO TFTs were investigated. It is found that channel layer thickness has strong impacts on the threshold voltage (V th ) and subthreshold swing (S.S.) of a‐IZBO TFTs. With increasing channel layer thickness, V th shifts to the negative direction, while S.S value decreases first and then increases. Increasing sputtering power also leads to the negative shift of V th . As sputtering power increases from 30 to 70 W, field effect mobility (µ FE ) increases from 18.2 to 25.4 cm 2 V ‐1 s ‐1 . However, at higher sputtering power, µ FE decreases to 19.6 cm 2 V ‐1 s ‐1 . As a result, the optimum a‐IZBO TFTs were obtained with channel layer thickness of 30 nm and sputtering power of 70 W.