Browsing by Author "Liu, Chuan"

Now showing 1 - 10 of 10

Electrically robust silver nanowire patterns transferrable onto various substrates
(2016)
Liu, Gui-Shi
;
Liu, Chuan
;
Chen, Hui-Jiuan
;
Cao, Wu
;
Qiu, Jing-Shen
We report a facile technique for patterning and transferring silver nanowires (AgNWs) onto various substrates. By employing only UV/O-3 and vapor treatment of hexamethyldisilazane (HMDS), we are able to accurately manipulate the surface energy via alternating the terminal groups of a polydimethylsiloxane (PDMS) substrate, so as to assist selective formation and exfoliation of AgNW films. A simple UV/O-3 treatment on PDMS enables uniform, well-defined, and highly conductive patterns of AgNWs after spin-coating. A vapor treatment of HMDS lowers the surface energy of the oxidized PDMS so that the patterned AgNWs embedded in an epoxy resin (EPR) are cleanly transferred from the PDMS to the target substrate. It is found that the AgNW-EPR composite on polyethylene glycol terephthalate (PET) exhibits remarkable durability under the bending test, tape test, ultrasonic treatment in water, and immersion of chemical solvents. In addition, we demonstrate that the AgNW-EPR composite work well as conductive patterns on the oxidized PDMS, polyvinyl alcohol (PVA), paper, and curved glass. The facile technique extends the applicability of AgNWs in the field of electronics, and it is potentially applicable to other nanomaterials.
Enhancing Performance in Thin Tilm Transistors with Vacuum or Solution Processed Amorphous Oxide Semiconductors Towards Display Applications
(2018-01-01)
Chen, Changdong
;
Li, Gongtan
;
Li, MinMin
;
Yang, Bo-Ru
;
Liu, Chuan
To simultaneously achieve high mobility and good reliability of thin-film transistors (TFTs), we controlled oxygen vacancies via nitrogen incorporation in InGaZnO TFTs from vacuum-or solution-based methods. For display applications, IGZO and crystalline silicon TFTs were integrated together to build hybrid CMOS. Also, additive patterning method is developed for solution-processed oxide semiconductors, based on which wafer-scale TFT arrays and NMOS have been demonstrated.
Integrating Poly-Silicon and InGaZnO Thin-Film Transistors for CMOS Inverters
(2017-09-01)
Chen, ChangDong
;
Yang, Bo-Ru
;
Liu, Chuan
;
Zhou, Xing-Yu
;
Hsu, Yuan-Jun
The applications of a-InGaZnO thin-film transistors (TFTs) to logic circuits have been limited owing to the intrinsic n-channel operation. In this paper, we demonstrated a hybrid inverter constructed by p-channel low-temperature poly-silicon (LTPS) TFTs and n-channel amorphous-indium-gallium-zinc-oxide (a-IGZO) TFTs. Hydrogenated LTPS TFTs and a-IGZO TFTs have been successfully fabricated on the same panel, followed by a rapid thermal annealing treatment to remove the hydrogens in the a-IGZO TFTs. The resulted hybrid inverter exhibits large noise margin closed to V-DD/2 and a high voltage gain as 68.3. Due to the complementary configurations in the static state, the inverter shows small current and thus consumes low power in hundreds of picowatts. As all the fabrication processes are compatible with conventional techniques, the reported results may open new opportunities in circuit design and applications for oxide TFTs.
Investigation of PVDF-TrFE composite with nanofillers for sensitivity improvement
(2016-07-01)
Chen, Hui-jiuan
;
Han, Songjia
;
Liu, Chuan
;
Luo, Zhenhua
;
Shieh, Han-Ping D.
Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) is a good candidate for wearable tactile sensing application, owing to its flexibility and easy processing. In this paper, we studied the effect of mixing silver nano-fillers with different morphologies into PVDF-TrFE to improve the extent of beta phase crystallization and the piezoelectric performance. After blending, the piezoelectric responding voltage of the composite was increased by a factor of more than three. This improvement results from the PVDF-TrFE chain arranges differently onto the nano-fillers with different morphologies, thus affects the crystallization. (C) 2016 Elsevier B.V. All rights reserved.
Microchannel Wetting for Controllable Patterning and Alignment of Silver Nanowire with High Resolution
(2015-09-30)
Yang, Bo-Ru
;
Cao, Wu
;
Liu, Gui-Shi
;
Chen, Hui-Jiuan
;
Noh, Yong-Young
Patterning and alignment of conductive nanowires are essential for good electrical isolation and high conductivity in various applications. Herein a facile bottom-up, additive technique is developed to pattern and align silver nanowires (AgNWs) by manipulating wetting of dispersions in microchannels. By forming hydrophobic/hydrophilic micropatterns down to 8 mu m with fiuoropolymer (Cytop) and SiO2, the aqueous AgNW dispersions with the optimized surface tension and viscosity self-assemble into microdroplets and then dry to form anisotropic AgNW networks. The alignment degree characterized by the full width at half-maximum (FWHM) can be well-controlled from 39.8 degrees to 84.1 degrees by changing the width of microchannels. A mechanism is proposed and validated by statistical analysis on AgNW alignment, and a static model is proposed to guide the patterning of general NWs. The alignment reduced well the electrical resistivity of AgNW networks by a factor of 5 because of the formation of efficient percolation path for carrier conduction.
Nitrogen-Doped Amorphous InZnSnO Thin Film Transistors With a Tandem Structure for High-Mobility and Reliable Operations
(2016-05)
Li, GongTan
;
Yang, Bo-Ru
;
Liu, Chuan
;
Lee, Chia-Yu
;
Wu, Yuan-Chun
The threshold voltage shift (Delta V-th) in amorphous InZnSnO thin-film transistors (a-IZTO TFTs) during negative gate-bias stress (NGBS) is significantly improved by nitrogen doping. Numerous N-In bonds eliminate donorlike subgap states near the Fermi level, which improve stability during stress but degrade electron mobility. We developed tandem TFTs with an a-IZTO:N layer on top of an a-IZTO layer, in which mobility reaches 31.76 +/- 0.81 cm(2)/Vs and the reliability is improved. Especially, Delta V-th in NGBS is reduced by 80% for pristine a-IZTO devices. This simple but an effective method achieves fast and reliable operation in the a-IZTO TFTs.
Positive gate bias instability alleviated by self-passivation effect in amorphous InGaZnO thin-film transistors
(2015-12-02)
Li, GongTan
;
Yang, Bo-Ru
;
Liu, Chuan
;
Lee, Chia-Yu
;
Tseng, Chih-Yuan
The threshold voltage shift (Delta Vth) under positive gate bias stress (PGBS), generally found in amorphous InGaZnO thin-film transistors (a-IGZO TFTs), has usually been suppressed by external passivation layers. We report it can also be alleviated by the self-passivation effect of the active layer, where moderately increasing the active layer thickness (d(s)) reduces Delta Vth by 82% in SiOx-passivated a-IGZO TFTs. Our experiments in conjunction with simulations show that the instability of V-th comes from ambient factors at the back channel. Larger d(s) results in lower carrier concentrations at the back channel (N-back), fewer diffusive ions affecting the front channel, and much more stable operations under PGBS. The optimal thickness of an IGZO film simultaneously obtaining a small Delta V-th, near-zero Vth, and sharp sub-threshold swing is about 80-90 nm, thicker than those usually adopted. The self-passivation effect combined with the externally deposited passivation layer can improve the overall device reliability.
Stability Enhancement of Silver Nanowire Patterns by Transferring Process
(2016)
Liu, Gui-Shi
;
Liu, Chuan
;
Chen, Jiuan-Hui
;
Shieh, Han-Ping D.
;
Yang, Bo-Ru
Silver nanowires (AgNWs) need to be patterned for using as transparent conductive electrodes (TCEs) in most electronic devices. Herein we propose a versatile technique which can fabricate AgNW patterns with enhanced adhesion to the substrate of polyethylene glycol terephthalate (PET). By using spin-coating, AgNWs were self-assembled into patterns on the surface of polydimethylsiloxane (PDMS) which had been patterned with high contrast of wettability by UV/O-3 exposure. To enhance the adhesion of AgNWs to substrate, the patterned AgNWs were embedded into epoxy resin (EPR) by a facile transferring process. The key to this process is the anti-adhesive groups (CH3) grafted on the oxidized PDMS to assist a clean exfoliation. The AgNW-EPR composite electrode exhibits excellent stability under adhesive tape test and long-term storage.
Subgap State Engineering Using Nitrogen Incorporation to Improve Reliability of Amorphous InGaZnO Thin-Film Transistors in Various Stressing Conditions
(2016-11)
Li, GongTan
;
Zhan, Runze
;
Yang, Bo-Ru
;
Liu, Chuan
;
Dong, ChengYuan
Instability of amorphous InGaZnO thin-film transistors (a-IGZO TFTs) remains an obstacle for commercialization. Here, we systematically discuss the effect of nitrogen incorporation on a-IGZO TFT stability and developed Ar/O-2/N-2 atmosphere to improve the stability under stressing in different conditions. Based on X-ray photoelectron spectrometer results, it is revealed that the positive gate bias stress (PGBS) stability is significantly improved due to microscopically passivated metal-oxygen bonds. Yet, the negative gate bias and light stress (NBLS) stability is seriously deteriorated with heavily nitrogen incorporation probably due to the bandgap narrowing effect. By optimizing a mixed O-2/N-2 atmosphere, the subgap states are finely tuned to afford optimal performance and stability. The developed IGZO TFTs exhibit mobility (12.67 cm(2)/Vs), small shift of threshold voltage under PGBS (reduced by 64% as compared with the pristine a-IGZO TFTs), and good negative gate bias stability and with NBLS stability as well.
TiO2 nanowire-templated hierarchical nanowire network as water-repelling coating
(2017-11-01)
Hang, Tian
;
Chen, Hui-Jiuan
;
Xiao, Shuai
;
Yang, Chengduan
;
Chen, Meiwan
Extraordinary water-repelling properties of superhydrophobic surfaces make them novel candidates for a great variety of potential applications. A general approach to achieve superhydrophobicity requires low-energy coating on the surface and roughness on nano-and micrometre scale. However, typical construction of superhydrophobic surfaces with micro-nano structure through top-down fabrication is restricted by sophisticated fabrication techniques and limited choices of substrate materials. Micro-nanoscale topographies templated by conventional microparticles through surface coating may produce large variations in roughness and uncontrollable defects, resulting in poorly controlled surface morphology and wettability. In this work, micro-nanoscale hierarchical nanowire network was fabricated to construct self-cleaning coating using one-dimensional TiO2 nanowires as microscale templates. Hierarchical structure with homogeneous morphology was achieved by branching ZnO nanowires on the TiO2 nanowire backbones through hydrothermal reaction. The hierarchical nanowire network displayed homogeneous micro/nano-topography, in contrast to hierarchical structure templated by traditional microparticles. This hierarchical nanowire network film exhibited high repellency to both water and cell culture medium after functionalization with fluorinated organic molecules. The hierarchical structure templated by TiO2 nanowire coating significantly increased the surface superhydrophobicity compared to vertical ZnO nanowires with nanotopography alone. Our results demonstrated a promising strategy of using nanowires as microscale templates for the rational design of hierarchical coatings with desired superhydrophobicity that can also be applied to various substrate materials.