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Ho IH, Chang CW, Chen YL, Chang WY, Kuo TJ, Lu YJ, Gwo S, Ahn H. Ultrathin TiN Epitaxial Films as Transparent Conductive Electrodes. ACS APPLIED MATERIALS & INTERFACES 2022; 14:16839-16845. [PMID: 35363462 DOI: 10.1021/acsami.2c00508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Titanium nitride (TiN), a transition-metal compound with tight covalent Ti-N bonding, has a high melting temperature and superior mechanical and chemical stabilities compared to noble metals. With a reduction in thickness, the optical transmittance of TiN films can be drastically increased, and in combination with its excellent electrical conductivity, the ultrathin and continuous TiN film can be considered as an ideal alternative of the metal oxide electrodes. However, the deposition of ultrathin and continuous metallic layer with a smooth surface morphology is a major challenge for typical deposition methods such as thermal evaporation or reactive sputtering. In particular, defects mainly related with oxygen contents and surface scattering can significantly limit the performance of ultrathin TiN films. In this work, ultrathin TiN films with 2-10 nm in thickness are grown by using the nitrogen plasma-assisted molecular-beam epitaxy (MBE) method in an ultrahigh vacuum environment. Excellent surface morphology with a root-mean-square roughness of ≤0.12 nm and a high optical transparency of 75% over the whole visible regime are achieved for ultrathin TiN epitaxial films. The dielectric properties determined by the spectroscopic ellipsometry and the electrical properties measured by the terahertz spectroscopy and the Hall effect method reveal that the percolation thickness of the TiN epitaxial film is less than 2.4 nm and its electrical conductivity is higher than 1.1 × 104 Ω-1 cm-1. These features make MBE-grown ultrathin TiN epitaxial films a good candidate for robust, low cost, and large-area transparent conductive electrodes.
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Affiliation(s)
- I Hong Ho
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
| | - Ching-Wen Chang
- Department of Physics, National Tsing-Hua University, Hsinchu 30013, Taiwan
| | - Yen-Lin Chen
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
| | - Wan-Yu Chang
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
| | - Ting-Jui Kuo
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
| | - Yu-Jung Lu
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Shangjr Gwo
- Department of Physics, National Tsing-Hua University, Hsinchu 30013, Taiwan
| | - Hyeyoung Ahn
- Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
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Characterization of Silver Nanowire Layers in the Terahertz Frequency Range. MATERIALS 2021; 14:ma14237399. [PMID: 34885553 PMCID: PMC8658758 DOI: 10.3390/ma14237399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/27/2021] [Accepted: 11/29/2021] [Indexed: 11/30/2022]
Abstract
Thin layers of silver nanowires are commonly studied for transparent electronics. However, reports of their terahertz (THz) properties are scarce. Here, we present the electrical and optical properties of thin silver nanowire layers with increasing densities at THz frequencies. We demonstrate that the absorbance, transmittance and reflectance of the metal nanowire layers in the frequency range of 0.2 THz to 1.3 THz is non-monotonic and depends on the nanowire dimensions and filling factor. We also present and validate a theoretical approach describing well the experimental results and allowing the fitting of the THz response of the nanowire layers by a Drude–Smith model of conductivity. Our results pave the way toward the application of silver nanowires as a prospective material for transparent and conductive coatings, and printable antennas operating in the terahertz range—significant for future wireless communication devices.
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Mei H, Zhang P, Zhang S, Yao R, Yao H, Chen F, Wang Z, Su F. Anisotropic terahertz transmission induced by the external magnetic field in La 0.67Ca 0.33MnO 3 film. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2021; 8:054301. [PMID: 34631932 PMCID: PMC8494497 DOI: 10.1063/4.0000123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
A systemic investigation of the terahertz (THz) transmission of La0.67Ca0.33MnO3 film on the (001)-oriented NdGaO3 substrate under external magnetic field and low temperature have been performed. The significant THz absorption difference between the out-of-plane and the in-plane magnetic field direction is observed, which is consistent with the electrical transport measurement using the standard four-probe technique. Furthermore, we find that the complex THz conductivities can be reproduced in terms of the Drude Smith equation as the magnetic field is perpendicular to the film plane, whereas it deviates from this model when the in-plane magnetic field is applied. We suggest that such anisotropies in THz transport dynamics have close correspondences with the phase separation and anisotropic magnetoresistance effects in the perovskite-structured manganites. Our work demonstrates that the THz time-domain spectroscopy (TDS) can be an effective non-contact method for studying the magneto-transport properties of the perovskite-structured manganites.
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Affiliation(s)
- Hongying Mei
- Henan Key Laboratory of Smart Lighting, School of Information Engineering, Huanghuai University, Zhumadian 463000, China
| | - Peng Zhang
- Fuyang Normal University, Fuyang 236037, China
| | - Shile Zhang
- High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Ruxian Yao
- Henan Key Laboratory of Smart Lighting, School of Information Engineering, Huanghuai University, Zhumadian 463000, China
| | - Haizi Yao
- Henan Key Laboratory of Smart Lighting, School of Information Engineering, Huanghuai University, Zhumadian 463000, China
| | - Feng Chen
- High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
| | - Zhenyou Wang
- Great Bay Area Research Institute, Aerospace Information Research Institute, Chinese Academy of Science, Guangzhou 510530, China
| | - Fuhai Su
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
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Huang ZW, Hong YH, Du YJ, Kuo TJ, Huang CC, Kao TS, Ahn H. Terahertz Analysis of CH 3NH 3PbI 3 Perovskites Associated with Graphene and Silver Nanowire Electrodes. ACS APPLIED MATERIALS & INTERFACES 2021; 13:9224-9231. [PMID: 33566570 DOI: 10.1021/acsami.0c21805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In order to investigate the thermal and chemical (in)stabilities of MAPbI3 incorporated with graphene and silver nanowire (AgNW) electrodes, we employed the terahertz (THz) time-domain spectroscopy, which has a unique ability to deliver the information of electrical properties and the intermolecular bonding and crystalline nature of materials. In in situ THz spectroscopy of MAPbI3, we observed a slight blue-shift in frequency of the 2 THz phonon mode as temperatures increase across the tetragonal-cubic structural phase transition. For MAPbI3 with the graphene top electrode, no noticeable frequency shift is observed until the temperature reaches the maximum operating temperature of solar cells (85 °C). Phonon frequency shift is sensitive to the strain-induced tilt of PbI6 octahedra and our results indicate that graphene forms a stable interface with MAPbI3 and is also effective in suppression of the undesirable phase transition. Meanwhile, for MAPbI3 coupled with the AgNW bottom electrode, the THz conductivity was found to be as low as that of the MAPbI3 single layer, attributed to the chemical reaction between Ag atoms and iodide ions. The THz conductivity is greatly increased when an ultrathin Al2O3 interlayer is introduced to cover the AgNW network via the atomic layer deposition (ALD) method. ALD of Al2O3 on the AgNW surfaces at low temperature guarantees a conformal coating, which strongly affects the ohmic contacts between the NWs. Our results demonstrate the advantage of THz spectroscopy for the comprehensive analysis of thermal and chemical stabilities of perovskites associated with the electrode materials.
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Affiliation(s)
- Zhi-Wei Huang
- Department of Photonics, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Yu-Heng Hong
- Department of Photonics, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Yi-Jheng Du
- Department of Photonics, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Ting-Jui Kuo
- Department of Photonics, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Chung-Che Huang
- Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, U.K
| | - Tsung Sheng Kao
- Department of Photonics, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Hyeyoung Ahn
- Department of Photonics, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
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Layani-Tzadka ME, Krotkov D, Tirosh E, Markovich G, Fleischer S. Contact-free conductivity probing of metal nanowire films using THz reflection spectroscopy. NANOTECHNOLOGY 2019; 30:215702. [PMID: 30695773 DOI: 10.1088/1361-6528/ab02b8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We utilize time-domain Terahertz (THz) reflectivity measurements for characterizing the surface conductivity of Polyethylene-terephthalate coated with nanowire (NW) films to form novel transparent electrodes (TE). We find good correspondence between the film conductivity and the THz-field reflectivity that provide uniquely desirable means for non-destructive, contactless conductivity measurements of large area NW-based-TEs. We demonstrate the robustness of THz reflectivity measurements to deviations invoked on NW film composition and film uniformity. The dependence of THz reflectivity on area NW coverage follows an anisotropic effective medium model for the dielectric constant.
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Yang J, Zhang Y, Zhang L, Wang H, Nie J, Qin Z, Li J, Xiao W. Analyte-triggered autocatalytic amplification combined with gold nanoparticle probes for colorimetric detection of heavy-metal ions. Chem Commun (Camb) 2018; 53:7477-7480. [PMID: 28480908 DOI: 10.1039/c7cc02198d] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
This work reports a new colorimetric nanosensor for the detection of heavy-metal ions that initially integrates analyte-triggered autocatalytic amplification with o-phenylenediamine-mediated aggregation of label-free gold nanoparticles. Its utility is well demonstrated with the simple, rapid, sensitive, and specific detection of Hg2+, Cu2+, and Ag+ targets with detection limits less than 3 nM.
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Affiliation(s)
- Juanhua Yang
- Collaborative Innovation Center for Water Pollution Control and Water Safety in Karst Area, Guangxi Key Laboratory of Electrochemical and Magnetochemical Function Materials, College of Chemistry and Bioengineering, Guilin University of Technology, 12 Jiangan Road, Guilin 541004, China.
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Study of a Particle Based Films Cure Process by High-Frequency Eddy Current Spectroscopy. COATINGS 2016. [DOI: 10.3390/coatings7010003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Kim HS, Patel M, Park HH, Ray A, Jeong C, Kim J. Thermally Stable Silver Nanowires-Embedding Metal Oxide for Schottky Junction Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2016; 8:8662-8669. [PMID: 26971560 DOI: 10.1021/acsami.5b12732] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Thermally stable silver nanowires (AgNWs)-embedding metal oxide was applied for Schottky junction solar cells without an intentional doping process in Si. A large scale (100 mm(2)) Schottky solar cell showed a power conversion efficiency of 6.1% under standard illumination, and 8.3% under diffused illumination conditions which is the highest efficiency for AgNWs-involved Schottky junction Si solar cells. Indium-tin-oxide (ITO)-capped AgNWs showed excellent thermal stability with no deformation at 500 °C. The top ITO layer grew in a cylindrical shape along the AgNWs, forming a teardrop shape. The design of ITO/AgNWs/ITO layers is optically beneficial because the AgNWs generate plasmonic photons, due to the AgNWs. Electrical investigations were performed by Mott-Schottky and impedance spectroscopy to reveal the formation of a single space charge region at the interface between Si and AgNWs-embedding ITO layer. We propose a route to design the thermally stable AgNWs for photoelectric device applications with investigation of the optical and electrical aspects.
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Affiliation(s)
- Hong-Sik Kim
- Photoelectric and Energy Device Application Lab (PEDAL) and Department of Electrical Engineering, Incheon National University , 119 Academy Road Yeonsu, Incheon 406772, Republic of Korea
| | - Malkeshkumar Patel
- Photoelectric and Energy Device Application Lab (PEDAL) and Department of Electrical Engineering, Incheon National University , 119 Academy Road Yeonsu, Incheon 406772, Republic of Korea
| | - Hyeong-Ho Park
- Applied Device and Material Lab., Device Technology Division, Korea Advanced Nano Fab Center (KANC) , Suwon 443270, Republic of Korea
| | - Abhijit Ray
- Solar Research and Development Center, Pandit Deendayal Petroleum University , Gandhinagar 382007, Gujarat, India
| | - Chaehwan Jeong
- Applied Optics and Energy Research Group, Korea Institute of Industrial Technology , Gwangju 500480, Republic of Korea
| | - Joondong Kim
- Photoelectric and Energy Device Application Lab (PEDAL) and Department of Electrical Engineering, Incheon National University , 119 Academy Road Yeonsu, Incheon 406772, Republic of Korea
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Hwang B, Park M, Kim T, Han SM. Effect of RGO deposition on chemical and mechanical reliability of Ag nanowire flexible transparent electrode. RSC Adv 2016. [DOI: 10.1039/c6ra10338c] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The role of RGO in chemical and mechanical reliability was studied for Ag nanowire/RGO hybrid electrode. RGO deposition can be effective in reducing the oxidation while maintaining the superior mechanical reliability under cyclic bendings.
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Affiliation(s)
- B. Hwang
- Graduate School of Energy Environment Water and Sustainability
- Korea Advanced Institute of Science & Technology
- Daejeon
- Republic of Korea
- BASF Electronic Materials R&D Center Asia
| | - M. Park
- Graduate School of Energy Environment Water and Sustainability
- Korea Advanced Institute of Science & Technology
- Daejeon
- Republic of Korea
| | - T. Kim
- Graduate School of Energy Environment Water and Sustainability
- Korea Advanced Institute of Science & Technology
- Daejeon
- Republic of Korea
| | - S. M. Han
- Graduate School of Energy Environment Water and Sustainability
- Korea Advanced Institute of Science & Technology
- Daejeon
- Republic of Korea
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Liu HC, Lai YC, Lai CC, Wu BS, Zan HW, Yu P, Chueh YL, Tsai CC. Highly effective field-effect mobility amorphous InGaZnO TFT mediated by directional silver nanowire arrays. ACS APPLIED MATERIALS & INTERFACES 2015; 7:232-240. [PMID: 25485556 DOI: 10.1021/am5059316] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this work, we demonstrate sputtered amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a record high effective field-effect mobility of 174 cm(2)/V s by incorporating silver nanowire (AgNW) arrays to channel electron transport. Compared to the reference counterpart without nanowires, the over 5-fold enhancement in the effective field-effect mobility exhibits clear dependence on the orientation as well as the surface coverage ratio of silver nanowires. Detailed material and device analyses reveal that during the room-temperature IGZO sputtering indium and oxygen diffuse into the nanowire matrix while the nanowire morphology and good contact between IGZO and nanowires are maintained. The unchanged morphology and good interfacial contact lead to high mobility and air-ambient-stable characteristics up to 3 months. Neither hysteresis nor degraded bias stress reliability is observed. The proposed AgNW-mediated a-IGZO TFTs are promising for development of large-scale, flexible, transparent electronics.
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Affiliation(s)
- Hung-Chuan Liu
- Department of Photonics, Institute of Electro-Optical Engineering, National Chiao Tung University , Hsinchu 300, Taiwan
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Chen JZ, Ahn H, Yen SC, Tsai YJ. Thermally induced percolational transition and thermal stability of silver nanowire networks studied by THz spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2014; 6:20994-20999. [PMID: 25402346 DOI: 10.1021/am5057618] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Great demand toward flexible optoelectronic devices finds metal nanowires (NWs) the most promising flexible transparent conducting material with superior mechanical properties. However, ultrathin metal nanowires suffer from relatively poor thermal stability and sheet conductance, attributed to the poor adhesivity of the ohmic contact between nanowires. Thermal heating and annealing at 200 °C increase the conductivity of the metal network, but prolonged annealing accelerates the breakage of NWs near the NW junction and the formation of Ag droplets. In this study, the thermal stability of silver NW (AgNW) films is investigated through the in situ measurements of sheet resistance and terahertz (THz) conductivity. With the improved ohmic contact at the NW junctions by heating, a characteristic transition from the subpercolative to percolative network is observed by in situ THz spectroscopy. It is found that stamp-transferred graphene incorporated with a near-percolative AgNW network can dramatically enhance the thermal stability of the graphene-AgNW (GAgNW) hybrid film. In both in situ measurements, little variation of physical parameters in GAgNW film is observed for up to 3 h of annealing. The presented results offer the potential of graphene-incorporated metal nanowire film as a highly conductive electrode that also has high thermal stability and excellent transparency for next-generation electronics and optoelectronics on flexible substrates.
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Affiliation(s)
- Jing-Zhi Chen
- Department of Photonics, National Chiao-Tung University , Hsinchu 30010, Taiwan, Republic of China
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Kim J, Oh J, In C, Lee YS, Norris TB, Jun SC, Choi H. Unconventional terahertz carrier relaxation in graphene oxide: observation of enhanced auger recombination due to defect saturation. ACS NANO 2014; 8:2486-2494. [PMID: 24494802 DOI: 10.1021/nn406066f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Photoexcited carrier relaxation is a recurring topic in understanding the transient conductivity dynamics of graphene-based devices. For atomically thin graphene oxide (GO), a simple free-carrier Drude response is expected to govern the terahertz (THz) conductivity dynamics--same dynamics observed in conventional CVD-grown graphene. However, to date, no experimental testimony has been provided on the origin of photoinduced conductivity increase in GO. Here, using ultrafast THz spectroscopy, we show that the photoexcited carrier relaxation in GO exhibits a peculiar non-Drude behavior. Unlike graphene, the THz dynamics of GO show percolation behaviors: as the annealing temperature increases, transient THz conductivity rapidly increases and the associated carrier relaxation changes from mono- to biexponential decay. After saturating the recombination decay through defect trapping, a new ultrafast decay channel characterized by multiparticle Auger scattering is observed whose threshold pump fluence is found to be 50 μJ/cm2. The increased conductivity is rapidly suppressed within 1 ps due to the Auger recombination, and non-Drude THz absorptions are subsequently emerged as a result of the defect-trapped high-frequency oscillators.
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Affiliation(s)
- Jaeseok Kim
- School of Electrical and Electronic Engineering, Yonsei University , Seoul 120-749, Korea
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