Jong Hyung Choi

Enhanced electron emission from carbon nanotubes through density control using in situ plasma treatment of catalyst metal

We controlled the density of carbon nanotubes (CNTs) through in situ NH3 plasma pretreatment and investigated field emission properties with the density variation. Ni catalytic layer was transformed into small nanoparticles with NH3 plasma pretreatment time and power. As NH3 plasma pretreatment time was increased, the growth rate of grown CNTs was gradually decreased. Also, the density of CNTs reduced from 2×109 to 8×106/cm2 with an increase in NH3 plasma pretreatment time from 10 to 30 min for the Ni layer of 10 A. With a decrease in the density of CNTs, the emission current density was increased and turn on electric field was decreased. We obtained large and uniform emission current (about 9 mA/emission area of 0.49 cm2) from CNTs film with the density of 8×106/cm2.

The interface formation and adhesion of metals (Cu, Ta, and Ti) and low dielectric constant polymer-like organic thin films deposited by plasma-enhanced chemical vapor deposition using para-xylene precursor

Abstract The interface formation, adhesion and diffusion properties of metals (Cu, Ta, and Ti) and low dielectric constant (low k ) polymer-like organic thin films (POTFs) deposited by plasma-enhanced chemical vapor deposition (PE-CVD) using the para -xylene precursor were investigated. Cu, Ta and Ti deposited on the surfaces of POTFs treated by O 2 and N 2 plasmas generated in a magnetically-enhanced inductively coupled plasma (ME-ICP) reactor. X-ray photoelectron spectroscopy (XPS) was used to study the chemical interactions between metals and POTFs. As a result of formation of new binding states by plasma treatment, the adhesion strength of metals and POTFs was increased. Diffusion properties of metals into POTFs were investigated using Rutherford backscattering spectroscopy (RBS) for the vacuum-annealed Cu/POTFs and Ta/POTFs for 1 h at 450°C. Also, from the RBS spectra, it was observed that Cu and Ta in the post-annealed samples were not diffused into both POTFs with and without plasma surface treatments.

Density control of carbon nanotubes using NH3 plasma treatment of Ni catalyst layer

Abstract The effect of NH 3 plasma pre-treatment on the growth characteristics of CNTs was investigated. We observed that NH 3 plasma pre-treatment etched and conglomerated Ni catalyst film, resulting in the formation of Ni nanoparticles. The aligned CNTs from the Ni nanoparticles were grown by plasma enhanced chemical vapor deposition (PECVD). As Ni film thickness decreased from 300 to 30 A, the size of Ni nanoparticles decreased about from 140 to 90 nm and the average diameter of CNTs became smaller. As the NH 3 plasma power was increased, the density of Ni nanoparticles was decreased, leading to the decrease in the density of CNTs.

Growth characteristics of carbon nanotubes via aluminum nanopore template on Si substrate using PECVD

Abstract Well ordered nano sized pore was fabricated on Si substrate using anodic oxidation method. Carbon nanotubes (CNTs) were grown on the well-ordered anodic aluminum oxide (AAO) template formed on Si substrate using plasma enhanced chemical vapor deposition with acetylene (C2H2). Without catalytic metal on the bottom of the AAO template, CNTs were grown on the top and within a nano-channel of the alumina template at 550 °C. The effect of process parameters such as plasma intensity, temperature and gas composition on the morphology of CNTs was investigated.

Relationship between field emission property and composition of carbon nanotube paste for large area cold cathode

CNT paste was made by mixture of multi-walled carbon nanotubes (MWNT) powder, organic vehicles and inorganic binder. Then firing process was performed at different temperature under air and N/sub 2/ atmosphere. It was found that emission property of CNT paste was changed by firing temperature due to remained resin. We obtained good emission property from CNT paste treated at 350/spl deg/C.

Control of carbon nanotubes density through Ni nanoparticle formation using thermal and NH3 plasma treatment

Abstract We controlled the size and distribution of catalytic Ni nanoparticles to control the density and diameter of carbon nanotubes (CNTs). With an increase in plasma power from 30 to 90 W for Ni layer of 30 A, the average diameter of particles decreased from 157 to 58 nm due to an enhanced etching effect. Size and distribution of Ni nanoparticles varied by plasma power, pre-treatment time and thickness of catalytic layer, resulting in the change in the density of grown CNTs. Density of CNTs reduced from 1×10 9 to 8×10 6 cm −2 , depending on the pre-treatment condition.

Enhanced electron emission from carbon nanotube paste after firing

After multi-walled carbon nanotubes (MWNT) powder was crushed with ball milling process, it was mixed with organic vehicles. And then CNT paste was printed on ITO coated glass substrate. The field emission characteristics of CNT pastes fired in air atmosphere was better than that of CNT paste fired in Ar ambient due to less organic residues after firing.