ZnO nanopencils: Efficient field emitters

Wang, R. C.; Liu, C. P.; Huang, Jow–Lay; Chen, S. J.; Tseng, Yung-Kuan; Kung, Sheng-Chin

doi:10.1063/1.1977187

Cited by 175 publications

(123 citation statements)

References 17 publications

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“…For SiC film deposited with 120W DC power, the turn-on field (defined as the E where the J can be distinguished from the background noise) was measured to be 4.5V/ m, the threshold field (defined as the E where the J is as high as 0.05mA/cm 2 ) was measured to be about 6.8V/ m and the field emission current density reached to 0.48mA/cm 2 at applied electric field of 10V/ m, which indicates that SiC thick film has high ratio of electron emission property. They are comparable to those values measured from other field emission materials, such as ZnO [8], etc. The field emission property of the SiC thick films was also investigated by the classical Fowler-Nordheim theory, which can be described as follows: , φ is the work function of the emission tip (eV), the factor describes the geometrical efficiency and equals to the percentage of the actual emitting surface area to the total surface area.…”

Section: Resultssupporting

confidence: 77%

Silicon Carbide Thin Film Deposited at Low Temperature by DC Magnetron Sputtering and Its Field Emission Property

Wei

2009

2009 Symposium on Photonics and Optoelectronics

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Abstract-The SiC thin films were successfully fabricated on Ptype <100> oriented silicon substrates at comparatively low temperature via DC magnetron sputtering deposition using a sintered SiC target with DC power of 120W. The deposition argon pressure was constantly at 2.0Pa. The as-grown SiC films were characterized by using X-ray diffraction, Atomic Force Microscope(AFM) and profilometer. The low turn-on field of about 4.5V/ m obtained from the field-emission property measurement at an anode-sample separation of 200 m shows that SiC films are competitive candidates for field-emission-based vacuum microelectronic devices.

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Section: Resultssupporting

confidence: 77%

Silicon Carbide Thin Film Deposited at Low Temperature by DC Magnetron Sputtering and Its Field Emission Property

Wei

2009

2009 Symposium on Photonics and Optoelectronics

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“…Similar results were also observed on NW samples with rough surfaces. 17,[23][24][25] In the growth process of GaN NWs with nanoscale protrusions, it is expected that the Ga vapor reacts with the N vapor, which is decomposed from the NH 3 at a high temperature of 950°C to form the GaN structure. It has been reported that hydrogen has a higher surface mobility and can stream easier and faster than the products of GaN molecules.…”

Section: Resultsmentioning

confidence: 99%

The Effect of Nanoscale Protrusions on Field-Emission Properties for GaN Nanowires

Lee

Shin

Chen

et al. 2007

J. Electrochem. Soc.

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GaN nanowires ͑NWs͒ have been synthesized on platinum-coated silicon͑111͒ substrates by the chemical vapor deposition ͑CVD͒ method under different NH 3 /H 2 carrier gas-flow rate ratios. X-ray diffractometer and transmission electron microscope analyses indicate that GaN NWs have wurtzite structures. Nanoscale protrusions with crystal orientation along the ͓002͔ direction were observed on the surface of GaN NWs grown under high H 2 flow rate conditions. As compared to the field-emission result of GaN NWs with smooth surfaces, GaN NWs with nanoscale protrusions exhibit a lower turn-on field of 8.5 V/m and a higher field-enhancement factor of ␤ = 315. These nanoscale protrusions are believed to account for the enhancement of the fieldemission behaviors of GaN NWs. Gallium nitride ͑GaN͒ has a wide direct bandgap of 3.4 eV at room temperature and is a popular semiconductor material with potential applications in blue and UV light emission, high temperature, and high power electronic devices.1,2 Recent efforts have been devoted to carbon nanotubes ͑CNTs͒ and ZnO nanostructures to improve the performance of conventional Spindt-type Mo field emitters. Because Mo, CNTs, and ZnO have a work function around 4.5 eV, sharp needlelike nanostructures are required to enhance electron emission with sufficient current density. GaN has attractive properties as a material for field emitters, e.g., a lower work function ͑4.1 eV͒ and stronger chemical and mechanical stability than those listed above. These properties make it a desired alternative material for field emitters. Typical GaN nanostructure morphologies include nanowires ͑NWs͒, nanorods, nanobelts, and nanotubes. Recently, needlelike 3 structures and quasi-aligned 4 GaN NWs have been grown and studies have shown that the sharp tip is responsible for the enhancement of the field-emission ͑FE͒ properties of NWs. The resulting turn-on field is ϳ7.5 V/m for needlelike 3 GaN NWs and ϳ7.0 V/m for quasi-aligned 4 GaN NWs. In these studies, the electrons were emitted from the tip of the NW due to its high aspect ratio. The FE characteristics of various GaN NWs created from different synthesizing methods are listed in Table I. All the GaN NWs listed in this table were grown under a constant flow rate of NH 3 . However, no study has ever been performed with different carrier gases, such as H 2 . This report not only shows the effect of different NH 3 /H 2 flow rate ratios on the growth and FE properties but also demonstrates the ability to use platinum as the catalyst for GaN NW growth of many other transition metals, such as Fe, Co, Ni, and Au. Nanoscale protrusions with crystal orientation along the ͓002͔ axis were first observed on the surface of GaN NWs that were grown under high H 2 flow rate conditions. The correlation between the FE behaviors and nanoscale protrusions were also explored in this report. ExperimentalGaN NWs were grown by thermally reacting metallic Ga ͑3 g͒ with different ratios of NH 3 /H 2 gases at 950°C for 30 min. In a horizontal quartz-tube furnace with a ...

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“…Such growth of nanowires on nanorods clearly shows that the two-stage process governed by the growth disparity along different facets indeed leads to preferential growth along the ½000 " 1 plane. 49 After a critical thickness is reached, the nanorods become nanowires, probably due to loss of substrate influence. This quasi-one-dimensional structure, as shown in the form of needles in Fig.…”

Section: Resultsmentioning

confidence: 99%

Catalyst-Free Direct Vapor-Phase Growth of Hexagonal ZnO Nanowires on α-Al2O3

Hullavarad

Vispute

et al. 2010

Journal of Elec Materi

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The evolution of ZnO nanowires has been studied under supersaturation of Zn metal species with and without a ZnO thin-film buffer layer on a-Al 2 O 3 deposited by the pulsed laser ablation technique. The nanowires had diameters in the range of 30 nm to 50 nm and lengths in the range of 5 lm to 10 lm with clear hexagonal shape and ½000 " 1, ½10 " 11, and ½10 " 10 facets. X-ray diffraction (XRD) measurements indicated crystalline properties for the ZnO nanostructures grown on pulsed laser deposition (PLD) ZnO nucleation layers. The optical properties were analyzed by photoluminescence (PL) and cathodoluminescence (CL) measurements. The ZnO nanowires were found to emit strong ultraviolet (UV) light at 386 nm and weak green emission as observed by PL measurements. The stoichiometry of Zn and O was found to be close to 1 by xray photoelectron spectroscopy (XPS) measurements. The process-dependent growth properties of ZnO nanostructures can be harnessed for future development of nanoelectronic components including optically pumped lasers, optical modulators, detectors, electron emitters, and gas sensors.

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ZnO nanopencils: Efficient field emitters

Cited by 175 publications

References 17 publications

Silicon Carbide Thin Film Deposited at Low Temperature by DC Magnetron Sputtering and Its Field Emission Property

Silicon Carbide Thin Film Deposited at Low Temperature by DC Magnetron Sputtering and Its Field Emission Property

The Effect of Nanoscale Protrusions on Field-Emission Properties for GaN Nanowires

Catalyst-Free Direct Vapor-Phase Growth of Hexagonal ZnO Nanowires on α-Al2O3

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