Sung Hoon Lim

Optical emission spectroscopy study for optimization of carbon nanotubes growth by a triode plasma chemical vapor deposition

We carried out the in situ analysis of chemical species for the growth of carbon nanotubes (CNTs), deposited by a triode plasma enhanced chemical vapor deposition with a C2H2 and NH3 mixture, using optical emission spectroscopy (OES). A positive mesh bias enhances the radical density, thus increasing the growth rate. The vertically aligned CNTs were grown at a 50% C2H2 flow rate ratio to NH3 and mesh bias voltage of +300V, resulting from the increased CH radical density and the decreased H and CN radical density through the OES analysis.

Self-organized carbon nanotips

We have developed a carbon nanostructure, which is comprised of high-density carbon nanotips on a graphite layer. These carbon nanotips, with tip diameters of ∼10 nm, are grown by high-density plasma chemical vapor deposition onto Ni-coated Si using an inductively coupled plasma. The Ni on Si changes into NiSi2 by substrate heating. First, a carbon buffer layer and then a graphene sheet are formed on the NiSi2. Then, the carbon nanotips are grown by a C2H2/H2 plasma on the graphene sheet. The carbon nanotips show good adhesion to the substrate and are almost aligned, with an average length of 110 nm. They exhibit a turn-on field of 0.1 V/μm, a field amplification factor of ∼13 000, a current density of 2 mA/cm2 at a field of 2 V/μm, and uniform electron emission.

Novel plasma chemical vapor deposition method of carbon nanotubes at low temperature for field emission display application

Abstract We developed a novel growth method of aligned carbon nanotubes. A high density plasma chemical vapor deposition (PECVD) has been employed to grow high-quality carbon nanotubes (CNTs) at low temperatures. High-density, aligned CNTs can be grown on Si and glass substrates. The CNTs were selectively-deposited on the patterned Ni catalyst layer, which was sputtered on Si. The CNTs exhibited a turn-on field of 0.9 V/μm and an emission current of 480 μA/cm 2 at a field of 3 V/μm.

Vertical alignment of nematic liquid crystal by rubbing-free method on the SiC thin film layer

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of the silicon carbide (SiC) thin film. The SiC thin film exhibits good chemical and thermal stability. The good thermal and chemical stability make SiC an attractive candidate for electronic applications. A vertical alignment of nematic liquid crystal by atomic beam exposure on the SiC thin film surface was achieved. The about 87° of stable pretilt angle was achieved at the range from 30 to 45° of incident angle. The good LC alignment is maintained by the atomic beam alignment method on the SiC thin film surface until annealing temperature of 300 °C. Consequently, the vertical alignment effect of liquid crystal and the good thermal stability by the atomic beam alignment method on the SiC thin film layer can be achieved.

High stability of emission current for a new carbon nanostructure film

Abstract We have studied the stability in the field emission currents for a carbon nanostructure which comprises of high-density carbon nanotips on Si. The emission current decreases by ∼18% after 50 h operation at ∼ 0.5 mA / cm 2 and it fluctuates by ±2% during operation. The high stability in emission current may be due to the high density of carbon tips and stable material property of graphite. The fluctuation may be due to the absorption and desorption of molecules to the tips in a vacuum chamber during electron emission.

Single standing carbon nanotube array in gate holes using a silicon nitride cap layer

We studied the growth of a single standing carbon nanotube (CNT) which was grown by plasma-enhanced chemical vapor deposition in the gate hole formed by conventional photolithography in the silicon nitride. The number of CNT per hole increases with increasing the gate hole diameter and a single CNT could be grown in a 3μm hole. A single standing CNT in a gate hole exhibited the turn-on field of 1.6V∕μm and the current density of 16μA at 3.3V∕μm. The emission currents follow the Fowler–Nordheim equation with a field enhancement factor of 1.14×107.

Spindt tip composed of carbon nanotubes

We report the synthesis of a cone-shaped bundle composed of carbon nanotubes (CNTs) in the gate holes by a multi-step growing method: (1) growth of carbon nanotubes in the gate hole; (2) etching the grown CNTs by in situ plasma treatment; (3) regrowth of CNTs. The new CNT bundle in the gate holes exhibited a turn-on gate voltage of 23.5V, an anode current density of 0.034mA∕cm2 at the gate voltage of 30V, and a transconductance of 2.05×10−4S; these are about 50% enhancement compared to conventional CNTs. The field emitter array with the Spindt-type CNTs in the gate holes shows uniform light emission.

P-42: High Luminance FED Lamp with Carbon Nanotip Emitter

The high density carbon nanotips were grown on the Si by high-density plasma chemical vapor deposition with inductively coupled plasma. The tips have 5∼10 nm radius with ∼100nm length. The high-brightness FED lamps of > 32,000 cd/m2 made of carbon nanotip emitter were demonstrated in this work.

P‐37: Field Emission from Carbon Nanotubes Grown by Layer‐by‐layer Deposition Method Using Plasma Chemical Vapor Deposition

We developed a noble carbon nanotube (CNT) deposition method using a layer-by-layer technique, in which the deposition of a thin layer CNT and a CF4 plasma exposure on its surface were carried out alternatively. Owing to the difference in the etch rate between amorphous carbon, graphite and CNTs by CF4 plasma, we can selectively etch away the unwanted amorphous carbon and graphite phases from the CNTs. The new CNTs deposited on glass substrate exhibited a turn-on field of 1.2 V/μm.

18.3: Low Temperature Carbon Nanotubes for Triode-Type Field-Emitter Array

We have developed a low temperature carbon nanotube (LT-CNT) growing process that can be used for electron emitter of field emission display (FED). Using this process technology, we successfully demonstrated a 5.4 inch LT-CNT FED using conventional 0.7 mm glass substrate without any distortion due to the thermal shrinkage of the glass substrate.