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Sunghoon Ahn - One of the best experts on this subject based on the ideXlab platform.
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MN2006-17031 MEASUREMENT OF MECHANICAL STRENGTH OF NANO COMPOSITE FABRICATED BY NANO COMPOSITE Deposition System (NCDS)
2020Co-Authors: Sung-geun Kim, Won-shik Chu, Hyung-jung Kim, Sunghoon AhnAbstract:ABSTRACT The rapid prototyping (RP) technology has been advanced for various applications such as verification of design, functional test. Recently, researchers have studied various materials to fabricate functional RP parts. In this research, a nano composite Deposition System (NCDS), which can fabricate various nano composites using polymer resins with various nano particles, was introduced. The NCDS is a hybrid System in which material removal process by mechanical micro machining and/or the Deposition process is combined. To predict the mechanical behavior of nano composite part made by NCDS, it is critical to understand the mechanical properties of the NCDS material. The NCDS process was characterizes by process parameters such as raster orientation, bead width, weight percent, and curing condition. Tensile strengths and compressive strengths of fabricated specimens with various raster orientation were measured, and various sample parts made of nano composites were fabricated using NCDS. INTRODUCTION The Rapid Prototyping technology has been advanced in product development cycle for more than 20 years. Relatively new approaches of RP cover micro scale devices such as micro-stereo lithography and various materials including ceramic and composite materials. Another promising area of RP application is bio and medical fields where simulation of operation by RP model is performed, and artificial bone made by RP is implanted into human body However, many RP machines still have the stair-step effect resulting in poor surface quality, time consuming post-process and limitation of applications for various materials. In this research, a nano composite Deposition System (NCDS) was developed to fabricate three dimensional nano composite parts. The NCDS uses polymer resins as matrix and various nano particles to form composite materials, an
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effect of particle size on various substrates for Deposition of nio film via nanoparticle Deposition System
Thin Solid Films, 2016Co-Authors: Hyungsub Kim, Sunghoon Ahn, Seungkyu Yang, Caroline Sunyong LeeAbstract:Abstract We report the Deposition mechanism of NiO particles using a nanoparticle Deposition System. To understand the effects of particle size and substrates on the Deposition, nano-, 100-nm-, sub-micro-, and micro-sized NiO particles were deposited on Si wafers, Ni-coated Si wafers, and fluorine-doped tin oxide (FTO)-coated glass. It was found that 100-nm- and nano-sized NiO particles were deposited, forming loosely compacted coating layers, by the breaking up of agglomerates, regardless of the type of substrate. In contrast, sub-micro- and micro-sized NiO particles formed dense and compact coating layers by deformation and fracturing on the Si and Ni-coated Si wafers. Moreover, sub-micro- and micro-sized NiO particles were not deposited on FTO glass; this was likely attributable to the NiO being harder than FTO glass and the micro-sized NiO particles would likely have rebounded on impact, resulting in no Deposition. Thus, the Deposition mechanism of NiO particles may be greatly related to the relative hardness difference between the NiO particles and the substrate. Moreover, it was found that different particle sizes resulted in different friction and mobility, based on response angle measurements, influencing the Deposition mechanism(s), especially at the interface. When the particle size was greater than 100 nm, the Deposition was due primarily to deformation and fracturing during the collision with the substrate. In particular, the 100-nm-sized NiO particles showed both mechanisms, a two-step process, with deformation or fracturing at the interface between the substrate and particles, followed by a loosely compacted coating layer forming, preserving the original particle shape. Thus, it was confirmed that the 100-nm-sized NiO particles were at or near a boundary for Deposition mechanisms. The effects of particle size and substrate for dry Deposition were explained successfully by assessing the Deposition behavior using analytical tools.
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low cost fabrication of wo3 films using a room temperature and low vacuum air spray based Deposition System for inorganic electrochromic device applications
Thin Solid Films, 2015Co-Authors: Sungik Park, Jungoh Choi, Sooyeun Kim, Ji Hyeon Song, Minoru Taya, Sunghoon AhnAbstract:Abstract We report the Deposition of tungsten oxide (WO3) thin films on fluorine-doped tin oxide (FTO) and indium-doped tin oxide (ITO) glass substrates by using a room-temperature Deposition System based on low-vacuum air-spray for the fabrication of inorganic electrochromic windows. The structure of the WO3 films was characterized using X-ray diffraction, and the surface morphology and film thickness were investigated using scanning electron microscopy and atomic force microscopy. The color of the prepared WO3 films changed from slight yellow to dark blue under applied voltages, demonstrating electrochromism. The WO3 film coated FTO glass exhibited a large electrochromic contrast of up to 50% at a wavelength of 800 nm. The electrochemical properties of the films were examined using cyclic voltammetry and chronocoulometry.
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nano particle Deposition System npds low energy solvent free dry spray process for direct patterning of metals and ceramics at room temperature
International Journal of Precision Engineering and Manufacturing, 2012Co-Authors: Dooman Chun, Jungoh Choi, Caroline Sunyong Lee, Isaku Kanno, Hidetoshi Kotera, Sunghoon AhnAbstract:With increasing concerns of environmental issues in manufacturing process, energy efficient and waste free manufacturing processes have been widely studied. In the field of nano/micro manufacturing, many research results of direct writing processes such as ink jet printing, gravure printing, and rapid prototyping processes have been reported to remove waste-producing conventional lift-off process for patterning. In addition, the use of toxic solvents such as acetone, toluene, xylene and so on has been decreased. At the same time, energy efficiency becomes one of environmental issues in manufacturing process. In this research, Nano particle Deposition System (NPDS), a dry spray Deposition process for fabrication of meta and ceramic direct patterning at room temperature, was introduced according to the environmental aspects. In previous studies, NPDS has shown the feasibility of the Depositions of metals such as Sn and Ni, and the Depositions of ceramics such as Al2O3, and TiO2 by spraying powders under low vacuum condition. The advantages of NPDS are 1) solvent free dry Deposition process, 2) relatively low energy consumption with room temperature and low vacuum process condition, and 3) direct patterning process. The energy consumption in NPDS was briefly compared with similar processes including aerosol Deposition and cold spray. The direct patterning results with 200μm width line pattern using micro-nozzle were fabricated without any post-processes. These results confirmed NPDS can become a solvent-free energy efficient direct patterning process for metals and ceramics.
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effect of stand off distance for cold gas spraying of fine ceramic particles 5μm under low vacuum and room temperature using nano particle Deposition System npds
Surface & Coatings Technology, 2012Co-Authors: Dooman Chun, Jungoh Choi, Caroline Sunyong Lee, Sunghoon AhnAbstract:Abstract The nano-particle Deposition System (NPDS) is a novel fabrication method for metallic and ceramic coatings at room temperature that sprays dry nano-sized powder or micro-sized powder without binders or additives. NPDS has been used to coat metal, ceramic, and polymer substrates with various metal and ceramic powders such as TiO 2 , Al 2 O 3 , Ni, and Sn. Deposition results have been reported, but the process parameters have not been evaluated in detail. The effect of the stand-off distance (SoD), which is an important process parameter and is easily controlled during fabrication, was evaluated in this study to better understand the process. Numerical analysis of the impact velocity of particles using the commercially available ANSYS CFX software package and experiments examining Al 2 O 3 Deposition on sapphire wafers (Al 2 O 3 ) using NPDS was carried out. In NPDS, the impact velocity of particles is one of the most important Deposition parameters because the sole energy source for bonding is the kinetic energy of the particles. The SoD range was set from 1 to 7 mm in 2-mm increments. Numerical analysis showed that the impact velocity of particles increased with increasing SoD. The impact velocity of particles correlated with the mechanical properties of the deposited layers. High impact velocity resulted in high mechanical properties for the deposited layer within the range of SoD tested. SoDs longer than 7 mm were not evaluated because the width and thickness of deposited layer were not suitable for patterning. Additionally, numerical analysis also helped explain the Deposition geometry, especially the width of the deposited pattern under the 1-mm SoD condition. The numerical analysis used in this study can be applied to research on the effects of other process parameters.
Dooman Chun - One of the best experts on this subject based on the ideXlab platform.
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nano particle Deposition System npds low energy solvent free dry spray process for direct patterning of metals and ceramics at room temperature
International Journal of Precision Engineering and Manufacturing, 2012Co-Authors: Dooman Chun, Jungoh Choi, Caroline Sunyong Lee, Isaku Kanno, Hidetoshi Kotera, Sunghoon AhnAbstract:With increasing concerns of environmental issues in manufacturing process, energy efficient and waste free manufacturing processes have been widely studied. In the field of nano/micro manufacturing, many research results of direct writing processes such as ink jet printing, gravure printing, and rapid prototyping processes have been reported to remove waste-producing conventional lift-off process for patterning. In addition, the use of toxic solvents such as acetone, toluene, xylene and so on has been decreased. At the same time, energy efficiency becomes one of environmental issues in manufacturing process. In this research, Nano particle Deposition System (NPDS), a dry spray Deposition process for fabrication of meta and ceramic direct patterning at room temperature, was introduced according to the environmental aspects. In previous studies, NPDS has shown the feasibility of the Depositions of metals such as Sn and Ni, and the Depositions of ceramics such as Al2O3, and TiO2 by spraying powders under low vacuum condition. The advantages of NPDS are 1) solvent free dry Deposition process, 2) relatively low energy consumption with room temperature and low vacuum process condition, and 3) direct patterning process. The energy consumption in NPDS was briefly compared with similar processes including aerosol Deposition and cold spray. The direct patterning results with 200μm width line pattern using micro-nozzle were fabricated without any post-processes. These results confirmed NPDS can become a solvent-free energy efficient direct patterning process for metals and ceramics.
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effect of stand off distance for cold gas spraying of fine ceramic particles 5μm under low vacuum and room temperature using nano particle Deposition System npds
Surface & Coatings Technology, 2012Co-Authors: Dooman Chun, Jungoh Choi, Caroline Sunyong Lee, Sunghoon AhnAbstract:Abstract The nano-particle Deposition System (NPDS) is a novel fabrication method for metallic and ceramic coatings at room temperature that sprays dry nano-sized powder or micro-sized powder without binders or additives. NPDS has been used to coat metal, ceramic, and polymer substrates with various metal and ceramic powders such as TiO 2 , Al 2 O 3 , Ni, and Sn. Deposition results have been reported, but the process parameters have not been evaluated in detail. The effect of the stand-off distance (SoD), which is an important process parameter and is easily controlled during fabrication, was evaluated in this study to better understand the process. Numerical analysis of the impact velocity of particles using the commercially available ANSYS CFX software package and experiments examining Al 2 O 3 Deposition on sapphire wafers (Al 2 O 3 ) using NPDS was carried out. In NPDS, the impact velocity of particles is one of the most important Deposition parameters because the sole energy source for bonding is the kinetic energy of the particles. The SoD range was set from 1 to 7 mm in 2-mm increments. Numerical analysis showed that the impact velocity of particles increased with increasing SoD. The impact velocity of particles correlated with the mechanical properties of the deposited layers. High impact velocity resulted in high mechanical properties for the deposited layer within the range of SoD tested. SoDs longer than 7 mm were not evaluated because the width and thickness of deposited layer were not suitable for patterning. Additionally, numerical analysis also helped explain the Deposition geometry, especially the width of the deposited pattern under the 1-mm SoD condition. The numerical analysis used in this study can be applied to research on the effects of other process parameters.
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Deposition mechanism of dry sprayed ceramic particles at room temperature using a nano-particle Deposition System
Acta Materialia, 2011Co-Authors: Dooman Chun, Sunghoon AhnAbstract:The nano-particle Deposition System (NPDS) is a new dry spray process used to deposit metal and ceramic particles at room temperature. Low temperature Deposition techniques for metals and ceramics that involve particle spraying include the NPDS, cold spray, and aerosol Deposition methods. These are widely used to minimize thermal damage to the substrate when fabricating metal or ceramic layers. To optimize the process conditions for the intended applications and improve the Deposition quality one must understand the mechanism of particle Deposition at room temperature. The bonding mechanism in metal particle Deposition by the cold spray method has already been researched. Adiabatic shear instability near the particle/substrate interface due to plastic deformation was reported to be the bonding mechanism for metal particles below the melting temperature. However, the bonding mechanism of ceramic particles has not been fully determined. This study assessed the bonding of ceramic particles by NPDS using numerical analysis and experimental results. A bonding mechanism is suggested after considering the experimental results for shock compaction, which is a process similar to that of the NPDS. The suggested Deposition mechanism for ceramics involves the fragmentation of submicron ceramic particles into nanoparticles and the successive impact of submicron particles, which provides sufficient bonding energy, with heat and high pressure, to nanoparticles fragmented by the shock wave.
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Nano particle Deposition System (NPDS) for ceramic and metal coating at room temperature and low vacuum condition
2008 International Conference on Smart Manufacturing Application, 2008Co-Authors: Dooman Chun, Minhyeng Kim, Jaechul Lee, Sunghoon AhnAbstract:Nano particle Deposition System (NPDS) is the newly developed ceramic and metal coating process. Nano and micro sized powders are sprayed through the supersonic nozzle at room temperature and low vacuum condition and deposited on various substrates. In this research, ceramic titanium dioxide (TiO2) coatings were deposited on metal substrates (SUS, Cu, Al) and polymer substrates (PET, PMMA), and metal tin (Sn) coating was deposited on SUS substrate. Coatings were fabricated with rectangular and line shapes at high Deposition rate and without causing thermal damage on the substrates. Deposition images and material properties such as chemical composition and morphology were measured. The test results showed that the NPDS provides a new coating method of ceramic and metal materials with large surface area.
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a nano particle Deposition System for ceramic and metal coating at room temperature and low vacuum conditions
International Journal of Precision Engineering and Manufacturing, 2008Co-Authors: Dooman Chun, Minhyeng Kim, Jaechul Lee, Sunghoon AhnAbstract:A new nano-particle Deposition System (NPDS) was developed for a ceramic and metal coating process. Nano-and micro-sized powders were sprayed through a supersonic nozzle at room temperature and low vacuum conditions to create ceramic and metal thin films on metal and polymer substrates without thermal damage. Ceramic titanium dioxide (TiO₂) powder was deposited on polyethylene terephthalate substrates and metal tin (Sn) powder was deposited on SUS substrates. Deposition images were obtained and the resulting chemical composition was measured using X-ray photoelectron spectroscopy. The test results demonstrated that the new NPDS provides a noble coating method for ceramic and metal materials.
Lyn M Irving - One of the best experts on this subject based on the ideXlab platform.
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stable zno thin film transistors by fast open air atomic layer Deposition
Applied Physics Letters, 2008Co-Authors: David Howard Levy, Diane Carol Freeman, Shelby Forrester Nelson, Peter Jerome Cowderycorvan, Lyn M IrvingAbstract:We report stable, high performance zinc oxide thin film transistors grown by an atmospheric pressure atomic layer Deposition System. With all Deposition and processing steps kept at or below 200°C, the alumina gate dielectric shows low leakage (below 10−8A∕cm2) and high breakdown fields. Zinc oxide thin film transistors in a bottom gate geometry yield on/off ratios above 108, near zero turn-on voltage, little or no hysteresis, and mobility greater than 10cm2∕Vs. With alumina passivation, shifts in threshold voltage under gate bias stress compare favorably to those reported in the literature.We report stable, high performance zinc oxide thin film transistors grown by an atmospheric pressure atomic layer Deposition System. With all Deposition and processing steps kept at or below 200°C, the alumina gate dielectric shows low leakage (below 10−8A∕cm2) and high breakdown fields. Zinc oxide thin film transistors in a bottom gate geometry yield on/off ratios above 108, near zero turn-on voltage, little or no hysteresis, and mobility greater than 10cm2∕Vs. With alumina passivation, shifts in threshold voltage under gate bias stress compare favorably to those reported in the literature.
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stable zno thin film transistors by fast open air atomic layer Deposition
Applied Physics Letters, 2008Co-Authors: David Howard Levy, Diane Carol Freeman, Shelby Forrester Nelson, Peter Jerome Cowderycorvan, Lyn M IrvingAbstract:We report stable, high performance zinc oxide thin film transistors grown by an atmospheric pressure atomic layer Deposition System. With all Deposition and processing steps kept at or below 200°C, the alumina gate dielectric shows low leakage (below 10−8A∕cm2) and high breakdown fields. Zinc oxide thin film transistors in a bottom gate geometry yield on/off ratios above 108, near zero turn-on voltage, little or no hysteresis, and mobility greater than 10cm2∕Vs. With alumina passivation, shifts in threshold voltage under gate bias stress compare favorably to those reported in the literature.
Caroline Sunyong Lee - One of the best experts on this subject based on the ideXlab platform.
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effect of particle size on various substrates for Deposition of nio film via nanoparticle Deposition System
Thin Solid Films, 2016Co-Authors: Hyungsub Kim, Sunghoon Ahn, Seungkyu Yang, Caroline Sunyong LeeAbstract:Abstract We report the Deposition mechanism of NiO particles using a nanoparticle Deposition System. To understand the effects of particle size and substrates on the Deposition, nano-, 100-nm-, sub-micro-, and micro-sized NiO particles were deposited on Si wafers, Ni-coated Si wafers, and fluorine-doped tin oxide (FTO)-coated glass. It was found that 100-nm- and nano-sized NiO particles were deposited, forming loosely compacted coating layers, by the breaking up of agglomerates, regardless of the type of substrate. In contrast, sub-micro- and micro-sized NiO particles formed dense and compact coating layers by deformation and fracturing on the Si and Ni-coated Si wafers. Moreover, sub-micro- and micro-sized NiO particles were not deposited on FTO glass; this was likely attributable to the NiO being harder than FTO glass and the micro-sized NiO particles would likely have rebounded on impact, resulting in no Deposition. Thus, the Deposition mechanism of NiO particles may be greatly related to the relative hardness difference between the NiO particles and the substrate. Moreover, it was found that different particle sizes resulted in different friction and mobility, based on response angle measurements, influencing the Deposition mechanism(s), especially at the interface. When the particle size was greater than 100 nm, the Deposition was due primarily to deformation and fracturing during the collision with the substrate. In particular, the 100-nm-sized NiO particles showed both mechanisms, a two-step process, with deformation or fracturing at the interface between the substrate and particles, followed by a loosely compacted coating layer forming, preserving the original particle shape. Thus, it was confirmed that the 100-nm-sized NiO particles were at or near a boundary for Deposition mechanisms. The effects of particle size and substrate for dry Deposition were explained successfully by assessing the Deposition behavior using analytical tools.
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nano particle Deposition System npds low energy solvent free dry spray process for direct patterning of metals and ceramics at room temperature
International Journal of Precision Engineering and Manufacturing, 2012Co-Authors: Dooman Chun, Jungoh Choi, Caroline Sunyong Lee, Isaku Kanno, Hidetoshi Kotera, Sunghoon AhnAbstract:With increasing concerns of environmental issues in manufacturing process, energy efficient and waste free manufacturing processes have been widely studied. In the field of nano/micro manufacturing, many research results of direct writing processes such as ink jet printing, gravure printing, and rapid prototyping processes have been reported to remove waste-producing conventional lift-off process for patterning. In addition, the use of toxic solvents such as acetone, toluene, xylene and so on has been decreased. At the same time, energy efficiency becomes one of environmental issues in manufacturing process. In this research, Nano particle Deposition System (NPDS), a dry spray Deposition process for fabrication of meta and ceramic direct patterning at room temperature, was introduced according to the environmental aspects. In previous studies, NPDS has shown the feasibility of the Depositions of metals such as Sn and Ni, and the Depositions of ceramics such as Al2O3, and TiO2 by spraying powders under low vacuum condition. The advantages of NPDS are 1) solvent free dry Deposition process, 2) relatively low energy consumption with room temperature and low vacuum process condition, and 3) direct patterning process. The energy consumption in NPDS was briefly compared with similar processes including aerosol Deposition and cold spray. The direct patterning results with 200μm width line pattern using micro-nozzle were fabricated without any post-processes. These results confirmed NPDS can become a solvent-free energy efficient direct patterning process for metals and ceramics.
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effect of stand off distance for cold gas spraying of fine ceramic particles 5μm under low vacuum and room temperature using nano particle Deposition System npds
Surface & Coatings Technology, 2012Co-Authors: Dooman Chun, Jungoh Choi, Caroline Sunyong Lee, Sunghoon AhnAbstract:Abstract The nano-particle Deposition System (NPDS) is a novel fabrication method for metallic and ceramic coatings at room temperature that sprays dry nano-sized powder or micro-sized powder without binders or additives. NPDS has been used to coat metal, ceramic, and polymer substrates with various metal and ceramic powders such as TiO 2 , Al 2 O 3 , Ni, and Sn. Deposition results have been reported, but the process parameters have not been evaluated in detail. The effect of the stand-off distance (SoD), which is an important process parameter and is easily controlled during fabrication, was evaluated in this study to better understand the process. Numerical analysis of the impact velocity of particles using the commercially available ANSYS CFX software package and experiments examining Al 2 O 3 Deposition on sapphire wafers (Al 2 O 3 ) using NPDS was carried out. In NPDS, the impact velocity of particles is one of the most important Deposition parameters because the sole energy source for bonding is the kinetic energy of the particles. The SoD range was set from 1 to 7 mm in 2-mm increments. Numerical analysis showed that the impact velocity of particles increased with increasing SoD. The impact velocity of particles correlated with the mechanical properties of the deposited layers. High impact velocity resulted in high mechanical properties for the deposited layer within the range of SoD tested. SoDs longer than 7 mm were not evaluated because the width and thickness of deposited layer were not suitable for patterning. Additionally, numerical analysis also helped explain the Deposition geometry, especially the width of the deposited pattern under the 1-mm SoD condition. The numerical analysis used in this study can be applied to research on the effects of other process parameters.
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measurement of anisotropic compressive strength of rapid prototyping parts
Journal of Materials Processing Technology, 2007Co-Authors: Caroline Sunyong Lee, Sungyong Kim, Hyung-jung KimAbstract:Abstract Rapid prototyping (RP) technologies provide the ability to fabricate initial prototypes from various model materials. Fused Deposition modeling (FDM) and 3D printer are commercial RP processes while nano composite Deposition System (NCDS) is an RP testbed System that uses nano composites materials as the part material. To predict the mechanical behavior of parts made by RP, measurement of the material properties of the RP material is important. Each process was characterizes by process parameters such as raster orientation, air gap, bead width, color, and model temperature for FDM. 3D printer and NCDS had different process parameters. Specimens to measure compressive strengths of the three RP processes were fabricated, and most of them showed anisotropic compressive properties.
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Deposition OF Al2O3 POWDERS USING NANO-PARTICLE Deposition System
2026Co-Authors: Woojin Song, Sunghoon Ahn, Dooman Chun, Kyubong Jung, Caroline Sunyong LeeAbstract:In this paper, alumina film was deposited using supersonic micronozzle in nano-particle Deposition System (NPDS). Powder Deposition at room temperature is important in the field of film Deposition since high processing temperature can be a serious limitation for the Deposition on flexible substrate. Previously, many studies have been reported on particle Deposition, such as aerosol Deposition method (ADM) or cold spray method. However, these Deposition methods cannot be applied to various types of powders. Recently, NPDS using aluminum nozzle was designed to resolve these problems but it cannot deposit precise patterns less than 1 mm. In this study, alumina particles were deposited using Silicon-based micronozzle in NPDS. Three-dimensional silicon micronozzle was fabricated using semiconductor processing method, specifically deep reactive ion etching (DRIE) method. The silicon micronozzle fabricated by Bosch process is advantageous over the conventionally used nozzle, since the hardness of silicon is higher than that of aluminum and the lifetime can be increased. In this study, alumina nano-particles were accelerated to supersonic level at the neck of micronozzle and deposited on the substrate in a low vacuum condition. The film characteristics were evaluated using field-emission scanning electronic microscope (FE-SEM) and alpha step to measure its thickness of the deposited layer. The Deposition result showed that alumina powders were successfully deposited using the fabricated micronozzle by means of NPDS.Alumina powers, micronozzle, DRIE, NPDS
David Howard Levy - One of the best experts on this subject based on the ideXlab platform.
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stable zno thin film transistors by fast open air atomic layer Deposition
Applied Physics Letters, 2008Co-Authors: David Howard Levy, Diane Carol Freeman, Shelby Forrester Nelson, Peter Jerome Cowderycorvan, Lyn M IrvingAbstract:We report stable, high performance zinc oxide thin film transistors grown by an atmospheric pressure atomic layer Deposition System. With all Deposition and processing steps kept at or below 200°C, the alumina gate dielectric shows low leakage (below 10−8A∕cm2) and high breakdown fields. Zinc oxide thin film transistors in a bottom gate geometry yield on/off ratios above 108, near zero turn-on voltage, little or no hysteresis, and mobility greater than 10cm2∕Vs. With alumina passivation, shifts in threshold voltage under gate bias stress compare favorably to those reported in the literature.We report stable, high performance zinc oxide thin film transistors grown by an atmospheric pressure atomic layer Deposition System. With all Deposition and processing steps kept at or below 200°C, the alumina gate dielectric shows low leakage (below 10−8A∕cm2) and high breakdown fields. Zinc oxide thin film transistors in a bottom gate geometry yield on/off ratios above 108, near zero turn-on voltage, little or no hysteresis, and mobility greater than 10cm2∕Vs. With alumina passivation, shifts in threshold voltage under gate bias stress compare favorably to those reported in the literature.
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stable zno thin film transistors by fast open air atomic layer Deposition
Applied Physics Letters, 2008Co-Authors: David Howard Levy, Diane Carol Freeman, Shelby Forrester Nelson, Peter Jerome Cowderycorvan, Lyn M IrvingAbstract:We report stable, high performance zinc oxide thin film transistors grown by an atmospheric pressure atomic layer Deposition System. With all Deposition and processing steps kept at or below 200°C, the alumina gate dielectric shows low leakage (below 10−8A∕cm2) and high breakdown fields. Zinc oxide thin film transistors in a bottom gate geometry yield on/off ratios above 108, near zero turn-on voltage, little or no hysteresis, and mobility greater than 10cm2∕Vs. With alumina passivation, shifts in threshold voltage under gate bias stress compare favorably to those reported in the literature.