High Performance Field Emission Research Articles

Single‐Crystalline CdS Nanobelts for Excellent Field‐Emitters and Ultrahigh Quantum‐Efficiency Photodetectors

The single crystalline CdS nanobelts were synthesized by an improved vapor-liquid-solid (VLS) process. Field emission measurements show that the nanostructures have a low turn-on field of 3.7 V&m-1 at a current density of 10 μA cm-1, a low threshold field of 9.3 V μm cm-1 and a high enhancement factor of 1298. When assembled into nanoscale visible light photodetectors, the CdS nanobelts showed good sensitivity and wavelength selectivity. The results imply that the present CdS nanobelts are excellent candidates for applications in high-performance field emitters and photodetectors.

Fabrication and enhanced field emission properties of novel silicon nanostructures

We reported the fabrication and the field emission properties of two-tier novel silicon nanostructures. First, silicon nanopillars with ordered high aspect ratio were achieved by using conventional lithographic techniques to act as the field emission sources. Second, sharp-edged well-aligned silicon nanograss was fabricated on top of the nanopillars by means of hydrogen plasma dry etching to induce the field emission characteristics. The turn-on fields were obtained as 10.5 and 14.4 V/μm under current density of 0.01 mA/cm 2 for two-tier patterns separated by respective 5 μm and 2 μm spaces. The excellent field emission property from these novel nanostructures exhibited a great potential as high-performance field emitter arrays towards future nanoelectronic devices.

Feasibility study of high performance field emitter pattern with the horizontally oriented carbon nanotubes by electrophoresis

For the field emitter applications, electrophoretic deposition (EPD) followed by post air annealing treatment was developed to selectively deposit the single-walled carbon nanotubes (SWNTs) pattern made of Al and SiO 2 coatings. The EPD was conducted from a solution mixture of SWNTs and various dispersants or surfactants, including sodium dodecyl sulfate (SDS), hexadecyl trimethyl ammonium bromide and trictylphosphine oxide. Effects of the processing parameters of EPD and the post air annealing treatment on SWNTs dispersion, morphology, field emission (FE), and film-substrate adhesion were examined. The results indicate that the SDS is the best surfactant in terms of SWNTs dispersion and solution stability, and the EPD parameters have no significant effects on their FE and adhesion properties of the deposited films. However, a higher post annealing temperature combined with an optimum annealing time is required to improve the film-substrate adhesion, so to reduce its electrical resistance and to enhance FE properties. The high performance annealed films with negligible internal stress are made of the micro-sized islands with the horizontally oriented SWNTs between them. The results also show that the pattern made of conductive and nonconductive coatings, such as Al and SiO 2, can be successfully used to deposit SWNTs pattern by EPD.

63.3: Active-Matrix Cathodes with Tapered Macro-Gate for High-Performance Field Emission Display

A color field emission display was developed with active-matrix cathodes and tapered macro-gate (TMG). The cascade-connected a-Si TFTs exhibited well controlled field emissions from carbon nanotube (CNT) emitters. The TMG protected the CNT emitters from the anode field perfectly, enabling us to apply a high anode voltage over 10 kV.

Deposition and field-emission characterization of electrically conductive nitrogen-doped diamond-like amorphous carbon films

For the fabrication of high performance field emitters, diamond-like amorphous carbon films doped with nitrogen (DAC:N) were formed using an intermittent supermagnetron plasma chemical vapor deposition technique. DAC:N films were deposited using isobutane plasma to investigate the influence of discharge-off time and electrode spacing on the physical properties of the films at upper- and lower-electrode radio frequency (rf) powers (LORF) of 800 W/50–800 W. At LORF of 100 W, a discharge-on time of 1 min, and a discharge-off time (cooling time) of 30 s–10 min, resistivity was decreased with a decrease of the cooling time. By reducing the electrode spacing from 60 to 20 mm at a LORF of 50 and 800 W, the optical band gap of DAC:N film was decreased from 0.85 and 0.23 eV to 0.6 and 0 eV, respectively. A flat DAC:N film of 700 A thickness was deposited on a n-Si wafer at rf powers of 800 W/800 W. Using this flat DAC:N film, a threshold electric field of 18 V/μm was observed and maximum field-emission current den...

25.3: Optimized Phosphors for Field Emission Displays

AbstractCandescent Technologies and SONY have developed the first commercially viable, full color, high performance field emission display (FED) which combines the premium visual performance of a color CRT in a thin flat panel package. Because of the similarity between the FED and CRT electron excitation, the FED can use the conventional P22 color CRT phosphor triad. However in this paper we will show improved performance for screens based on phosphors optimized for the lower accelerating voltage of the FED (7–10 kV). Data will be presented showing screen performance in full color FED's including color gamut, white screen brightness and luminous efficacy. This data will compare optimized phosphors with the P22 color CRT phosphors. The most striking improvement has been seen for the ZnS:Ag blue phosphor where the optimized phosphor shows higher efficacy, superior color saturation, and improved maintenance of efficacy with coulombic aging when compared to the P22 blue phosphor. Factors which influence the phosphor performance will be discussed including activator and co‐activator concentration as well as phosphor crystal structure as measured by cross sectional TEM.

Extracting Low Energy X-Ray Peaks From EDS and WDS Spectra

Abstract Interest in electron beam x-ray microanalysis with low incident beam energies, defined arbitrarily as 5 keV and below, has been greatly stimulated in recent years by the development of the high performance field emission gun scanning electron microscope (FEG-SEM), which can produce a nanometer-scale probe with sufficient current to operate with both energy dispersive (EDS) and wavelength dispersive (WDS) spectrometers. Microanalysis in this regime requires the analyst to confront new spectrometry problems that are not typically encountered, or that can be safely ignored, when operating with conventional beam energies, 10 keV or greater. With low energy operation, the choice of atomic shells that can be accessed is restricted, forcing the analyst to make use of shells that have low fluorescence yields for intermediate and high atomic number elements, and possibly strong chemical effects, which are evident with high resolution x-ray spectrometry.

High performance field-emission electron gun and its applications to electron phase microscopy

High performance field-emission electron gun and its applications to electron phase microscopy

High performance field-emission column for next generation E-Beam Tester

Electron beam testing is a state-of-the-art method for design verification and failure analysis of highly integrated devices. The progressive development in IC complexity and performance, however, is forcing a rapid evolution in electron beam testing technology. The instrumentation required for the next generation of devices must be capable of probing lines with geometries under half a micrometer with GHz signals applied. In accordance with these needs, a new E-Beam Tester has been developed. By applying field emission technology to electron probe generation, a remarkable increase in performance has been obtained by comparison with conventional systems. An extremely high beam current is focused to a probe of 50 nm diameter. With this precise signal measurements with 10 GHz bandwidth can be performed, such as delay measurements with a time resolution of better than 10 ps. The measurement voltage accuracy of low amplitude signals in the mV-range also benefits from the improved probe performance.

Knife-edge thin film field emission cathodes on (110) silicon wafers

In the effort to develop a high performance field emission cathode for application in microwave amplifiers, it is clear that the emitter structure should have a sharp emitter surface, a large emitter height, a small gate opening size, and a small emitter angle. We have developed a technique that fabricates knife-edge field emission arrays (KEFEA) on (110) silicon wafers. KEFEA has an optimized structure meeting the requirements mentioned above. The emitter edge radius is about 250 Å or less, the emitter height is 8 μm, and the gate gap is ∼0.2 μm. Experiments have exhibited Fowler–Nordheim type field emission with gate-to-substrate bias voltage less than 50 V.

Direct Defect Imaging in the High Resolution Sem

AbstractThe theory of imaging crystallographic defects in solid specimens through the use of electron channeling contrast is reviewed and the necessary conditions for observation are deduced. It is shown that current high performance field emission scanning electron microscopes can meet these requirements and produce dislocation images from suitable materials.

Low-voltage high-resolution Scanning Electron Microscopy of semiconductors

The advent of scanning electron microscopes (SEMs) with reliable, high performance field emission guns (FEG) has afforded many opportunities to obtain new information at low voltages not available at higher voltages in traditional SEMs equipped with tungsten hairpin or LaB6 filaments. The FEG SEMs are able to operate at low voltages with both high brightness and high resolution (HR) due to the small source size and low energy spread of the beam. Resolution of 4 nm down to 1.5 nm are routinely possible in the energy range from 1 to 5 keV along with standard image recording times of 1 to 2 minutes. The low voltage capabilities have allowed insulating materials, such as polymers, composites, and ceramics to be imaged at high resolutions at energies below the second crossover, usually around 1 to 2 keV, without experiencing image artifacts from negative surface charging normally found in uncoated insulators at higher operating voltages.

Current State of Biological High-Resolution Scanning Electron Microscopy

A new generation of high performance field emission scanning electron microscopes (FSEM) is now commercially available (JEOL 890, Hitachi S 900, ISI OS 130-F) characterized by an "in lens" position of the specimen where probe diameters are reduced and signal collection improved. Additionally, low voltage operation is extended to 1 kV. Compared to the first generation of FSEM (JE0L JSM 30, Hitachi S 800), which utilized a specimen position below the final lens, specimen size had to be reduced but useful magnification could be impressively increased in both low (1-4 kV) and high (5-40 kV) voltage operation, i.e. from 50,000 to 200,000 and 250,000 to 1,000,000 x respectively.At high accelerating voltage and magnification, contrasts on biological specimens are well characterized1 and are produced by the entering probe electrons in the outmost surface layer within -vl nm depth. Backscattered electrons produce only a background signal. Under these conditions (FIG. 1) image quality is similar to conventional TEM (FIG. 2) and only limited at magnifications >1,000,000 x by probe size (0.5 nm) or non-localization effects (%0.5 nm).