• 한국정보디스플레이학회:학술대회논문집
• /
• 2000.01a
• /
• pp.231-234
• /
• 2000

Vertically aligned carbon nanotubes were synthesized on Ni-coated Si substrates using microwave plasma-enhanced chemical vapor deposition. The grain size of Ni thin films was varied with the RF power density during the RF magnetron sputtering process. It was found that the diameter, growth rate, and density of carbon nanotubes could be controlled systematically by the grain size of Ni thin films. With decreasing the grain size of Ni thin films, the diameter of the nanotubes decreased, whereas the growth rate and density increased. High-resolution transmission electron microscope images clearly demonstrated synthesized nanotubes to be multiwalled. The number of graphitized wall decreased with decreasing the diameter. Field emission properties will be further presented.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.8
• /
• pp.657-662
• /
• 2003

This paper presents a new fabrication method of selective SiGe epitaxial growth at 650 $^{\circ}C$ on (100) silicon wafer with oxide patterns by reduced pressure chemical vapor deposition. The new method is characterized by a cyclic process, which is composed of two parts: initially, selective SiGe epitaxy layer is grown on exposed bare silicon during a short incubation time by SiH$_4$/GeH$_4$/HCl/H$_2$system and followed etching step is achieved to remove the SiGe nuclei on oxide by HCl/H$_2$system without source gas flow. As a result, we noted that the addition of HCl serves not only to reduce the growth rate on bare Si, but also to suppress the nucleation on SiO$_2$. In addition, we confirmed that the incubation period is regenerated after etching step, so it is possible to grow thick SiGe epitaxial layer sustaining the selectivity. The effect of the addition of HCl and dopants incorporation was investigated.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1440-1441
• /
• 2006

In this study, we synthesized CNTs(carbon nanotubes) on the glass substrate by microwave plasma enhanced chemical vapor deposition (MPECVD), Effect of bias voltage on the grown behavior and morphology of CNTs were investigated. Recently, it has been proposed that aligned CNTs can also be achieved by the application of electric bias to the substrate during growth, the first time reported the bias effect such that the nanotube alignment occurred only when a positive bias was applied to the substrate whereas no aligned growth occurred under a negative bias and no tube growth was observed without bias. On the country, several researchers reported some different observations that aligned nanotubes could also be grown under negative substrate biases. This discrepancy as for the effect of positive and negative bias may indicate that the bias effect is not fully understood yet. The glass and Si wafers were first deposited with TiN buffer layer by r.f sputtering method, and then Ni catalyst same method, The thickness of TiN and Ni layer were 200 nm and 60 nm, respectively. The main process parameters include the substrate bias (0 to - 300 V), and deposition pressure (8 to 20 torr).

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.283.2-283.2
• /
• 2013

The variation of chemical and interfacial state during the growth of Ta2O5 films on the Si substrate by atomic layer deposition (ALD) was investigated using in-situ synchrotron radiation photoemission spectroscopy. A newly synthesized liquid precursor Ta(NtBu)(dmamp)2Me was used as the metal precursor, with Ar as a purging gas and H2O as the oxidant source. The core-level spectra of Si 2p, Ta 4f, and O 1s revealed that Ta suboxide and Si dioxide were formed at the initial stages of Ta2O5 growth. However, the Ta suboxide states almost disappeared as the ALD cycles progressed. Consequently, the Ta5+ state, which corresponds with the stoichiometric Ta2O5, only appeared after 4.0 cycles. Additionally, tantalum silicate was not detected at the interfacial states between Ta2O5 and Si. The measured valence band offset value between Ta2O5 and the Si substrate was 3.08 eV after 2.5 cycles.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.3
• /
• pp.273-278
• /
• 2014

On poly and single crystalline Cu substrates, the graphene was synthesized by chemical vapor deposition(CVD). Optical microscopic images which were not possible to show the detailed characterization of graphene growth were adjusted and analyzed using image analyzing software. As a result it was possible to show the detailed growth mechanism of graphene by utilizing the image analysis. Nucleation of graphene on Cu grain boundary and its growth behavior into Cu grain are shown. In addition, the movement of graphene grain boundary interacting with Cu grain boundary and pinholes during growth was illustrated in detail, and the cause and result are discussed as a result of those interactions.

• Transactions of Materials Processing
• /
• v.29 no.1
• /
• pp.44-48
• /
• 2020

Aluminum nitride (AlN), as a substrate material in electronic packaging, has attracted considerable attention over the last few decades because of its excellent properties, which include high thermal conductivity, a coefficient of thermal expansion that matches well with that of silicon, and a moderately low dielectric constant. AlN films with c-axis orientation and thermal conductivity characteristics were deposited by using Pulsed Laser Deposition (PLD). The epitaxial AlN films were grown on sapphire (c-Al₂O₃) single crystals by PLD with AlN target and Y₂O₃ doped AlN target. A comparison of different targets associated with AlN films deposited by PLD was presented with particular emphasis on thermal conductivity properties. The quality of AlN films was found to strongly depend on the growth temperature that was exerted during deposition. AlN thin films deposited using Y₂O₃-AlN targets doped with sintering additives showed relatively higher thermal conductivity than while using pure AlN targets. AlN thin films deposited at 600℃ were confirmed to have highly c-axis orientation and thermal conductivity of 39.413 W/mK.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.160-160
• /
• 2011

In the present work, $TiO_2$ fiilms supported by porous silica gel with high surface area synthesized by atomic layer deposition(ALD). Porous structure of silica substrate could be maintained even after deposit large amount of $TiO_2$ (500 cycles of ALD process), suggesting the differential growth mode of $TiO_2$ on top surface and inside the pore. All the $TiO_2$-covered silica samples showed improved MB adsorption abilities, comparing to bare one. In addition, when silica surface was covered with $TiO_2$ films, MB adsorption capacity was almost fully recovered by re-annealing process (500$^{\circ}C$, for 1 hr, in ambient pressure), whereas MB adsorption capacity of bare silica was decreased after re-heaing process. FT-IR study demonstrated that $TiO_2$ film could prevent deposition of surface-bound intermediate species during thermal decomposition of adsorbed MB molecules. Photocatalytic activity of $TiO_2$/silica sample was also investigated.

• Journal of the Korean Vacuum Society
• /
• v.21 no.2
• /
• pp.86-92
• /
• 2012

We have studied the effect of speed of deposited atom on morphology evolution during Glancing Angle Deposition (GLAD). Using Kinetic Monte Carlo simulation that incorporate molecular dynamics simulations, we have shown that the rough surface morphology became smoother as the speed of deposited atom is increased. The growth exponent ${\beta}$ change from 0.97 to 0.67 as the speed increase from ${\upsilon}_0$ to $10{\upsilon}_0$ in the case of GLAD. We also examined the effect of speed of deposited atom for the case of chemical vapor deposition (CVD) simulation. Compared to GLAD, the variation in scaling exponent ${\beta}$ is small but the speed of deposited atom also have considerable effect on growth morpholgy in the case of CVD.

• Journal of the Korean Vacuum Society
• /
• v.22 no.1
• /
• pp.31-36
• /
• 2013

For the simplification of doping process in amorphous carbon film, arsenic (As) ions were implanted on the nucleated silicon wafer before the growth process. Then amorphous carbon films were grown at the condition of $CH_4/H_2=5%$ by microwave plasma chemical vapour deposition. Because the implanted seeds were grown at the high temperature and the implanted ions were spread, it was possible to reduce the process steps by leaving out the annealing process. When the implanted amorphous carbon films were electrically characterized in diode configuration, field emission current of $0.1mA/cm^2$ was obtained at the applied electric field of about $2.5V/{\mu}m$. The results show that the implanted As ions were sufficiently doped by the self-annealing process by using the growth after implantation.

• Proceedings of the KIEE Conference
• /
• 2001.11a
• /
• pp.12-15
• /
• 2001

Polycrystalline diamond films are deposited by cyclic method. modulating the $H_2$ Plasma and $CH_4+H_2$ plasma during the growth step. Diamond quality is evaluated by FWHM and $I_D/I_G$ ratio obtained from Raman spectroscopic analysis. Structural defects and impurities generated during the growth step are characterized by cathodoluminescence, and the variations between band-A(430 nm) line and nitrogen-related(578 nm) line are investigated as a function of $T_E/T_G$. Furthermore, the correlations between preferential orientation. film morphologies and CL characteristics are also investigated.