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Improvement of electrical characteristics in the solution‐processed nanocrystalline indium oxide thin‐film transistors depending on yttrium doping concentration
Author(s) -
Ting ChuChi,
Fan HsinYun,
Tsai MengKun,
Li WeiYang,
Yong HuaEn,
Lin YenFeng
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.201330164
Subject(s) - thin film transistor , materials science , thin film , doping , yttrium , analytical chemistry (journal) , field effect , threshold voltage , indium , nanocrystalline material , surface roughness , saturation (graph theory) , optoelectronics , oxide , layer (electronics) , transistor , nanotechnology , electrical engineering , voltage , composite material , metallurgy , chemistry , mathematics , engineering , chromatography , combinatorics
Y 3+ (0, 6, 12, or 20 mol%)‐doped In 2 O 3 (YInO; YIO) thin films were fabricated by the sol–gel spin‐coating technique, and they were used as the active layer of thin‐film transistor (TFT) devices. The YIO‐TFTs operate in the n‐channel enhancement mode and exhibit a well‐defined pinch‐off and saturation region. The Y 3+ (12 mol%)‐doped In 2 O 3 TFT possesses the optimal performance, and its field‐effect mobility in the saturated regime, threshold voltage, on–off ratio, and S factor are 0.95 cm 2 V −1 s −1 , 6.74 V, 1.55 × 10 5 , and 2.37 V decade −1 , respectively. The yttrium ion can act as the carrier suppressor to reduce the carrier concentration of In 2 O 3 thin film because of its lower electronegativity (1.22) and standard electrode potential (−2.372 V). The carrier concentrations and conductivities of In 2 O 3 thin films decrease from 2.5 × 10 14 to 3.8 × 10 11 cm −3 , and 14.3 to 1.5 × 10 −4 S m −1 , respectively, with the increase of Y 3+ doping concentrations from 0 to 12 mol%. In addition, the Y 3+ (12 mol%)‐doped In 2 O 3 thin film also possesses the minimal surface roughness (4.19 nm) and lowest trap states (1.07 × 10 13 ). Therefore, by Y 3+ doping the electrical properties of In 2 O 3 thin films can be improved to match the basic requirement of the TFT devices.