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Page 16 of 39 Jeon et al. Soft Sci. 2025, 5, 1 https://dx.doi.org/10.20517/ss.2024.35

Table 4. Summarized high-performance MO TFTs with high-k dielectrics

Gate Deposition Channel T μ FE SS On/off
Approach Substrate max 2 -1 -1 Refs. Year
dielectric method materials (°C) (cm ·V ·s ) (V/decade) ratio
MO dielectric - Al O 3 Spin coating IGZO PI 350 84.4 - 10 5 [72] 2014
2
monolayer 9
ALD IZO PI 200 42.1 0.29 10 [134] 2016
ALD ZnO PET 100 37.1 0.38 10 7 [135] 2019
ALD IGZO PI 350 47.9 0.18 - [136] 2019
ALD ZnON PEN 150 147 0.21 - [113] 2020
11
HfO ALD IGZO PI 200 19 0.09 10 [150] 2020
2
7
ZrO x Spin coating LiZnO PI 350 48.47 0.26 10 [114] 2021
8
MO dielectric - Ga O /ZrO Spin coating ZnO PI 350 41 0.22 10 [98] 2022
2 3 x
multilayer 5
Y O /TiO /Y O 3 Electron beam IGZO PC - 40 0.16 10 [138] 2013
2
3
2
2
evaporation
5
SiO /TiO /SiO Electron beam IGZO PC RT 76 0.13 10 [139] 2013
2 2 2
evaporation
HfO /TiO Evaporator TiO /IGZO PC 100 61 0.13 - [82] 2014
2 2 x
Zr-Al O 3 Spin coating IZO PI 280 51 - 10 4 [141] 2013
2
7
Al O :Nd Anodization ZrInO PEN 150 22.6 0.39 10 [142] 2016
2 3
process
6
Polymer Electrolyte Drop casting In O PI 250 8.74 10 [147] 2020
2 3
dielectric 6
Electrolyte Drop casting, spin IGZO PI 120 42 0.18 10 [148] 2018
coating
7
PVP-co- Spin cast IGTO PI/PDMS 150 25.9 0.4 10 [149] 2019
PMMA:HfO x
MO: Metal oxide; TFTs: thin-film transistors; SS: subthreshold swing; ALD: atomic layer deposition; IGZO: indium gallium zinc oxide; PI: polyimide;
IZO: indium zinc oxide; PET: polyethylene terephthalate; PEN: polyethylene naphthalate; PC: polycarbonate; RT: room temperature; PVP-co-
PMMA: poly(4-vinylphenol-co-methyl methacrylate); IGTO: indium gallium tin oxide; PDMS: polydimethylsiloxane.
performance of MO semiconductors. Incorporating hydrogen atoms into the oxide lattice can passivate
defects and increase carrier mobility [59,152,153,155-157] . This process is typically done through thin film deposition
in hydrogen atmosphere [152,156] , hydrogen plasma treatment [153,155] or MO thin film in a hydrogen
atmosphere [59,151,154] . Recently, Lee et al. investigated the diffusion of hydrogen from plasma-enhanced ALD
(PEALD)-derived SiO into the underlying a-IGZTO film during the post-deposition annealing (PDA)
2
process. The transfer curves of the TFTs that optimized IGZTO thin films are shown in Figure 6A.
Compared with those without PDA (field-effect mobility = 19.1 cm /Vs), the devices conducting PDA
2
2
process exhibited a higher field-effect mobility of 85.9 cm /Vs in Figure 6A . The hydrogen atoms help
[59]
reduce trap states, can act as a shallow donor in MO semiconductors, and improve the overall conductivity
of the semiconductor layer, leading to enhanced device performance with higher mobility and lower
subthreshold swing [169,170] . However, since hydrogen doping can cause a significant negative shift in the
threshold voltage (V ) and undesirable photo-instability [171,172] , Abliz et al. demonstrated the effects of co-
TH
plasma treatment with hydrogen and nitrogen on IGZO TFTs to enhance both electrical performance and
stability simultaneously .
[157]
Fluorine doping is a technique used to improve the stability and electrical performance of MO
semiconductors. Fluorine atoms, due to their high electronegativity, can effectively passivate defect sites and
reduce the density of oxygen vacancies. This leads to a decrease in off-state leakage current and an
improvement in threshold voltage stability. The amount of F in MO films was carefully controlled and
introduced to ZnO , ZTO [164,166] , IGZO [167,168] , InO x [173] and IWZO films to enhance electrical properties,
[163]
[165]
achieving a field-effect mobility of 31.59 cm /Vs in ZnO TFTs . Recently, Li et al. developed high-
[163]
2