• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.480-480
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• 2010

In the present work, we studied effect of the deposition parameters on the structure and properties of ZnO films deposited by DC arc plasmatron. The varied parameters were gas flow rates, precursor composition, substrate temperature and post-deposition annealing temperature. Vapor of Zinc acetylacetone was used as source materials, oxygen was used as working gas and argon was used as the cathode protective gas and a transport gas for the vapor. The plasmatron power was varied in the range of 700-1,500 watts. Flow rate of the gases and substrate temperature rate were varied in the wide range to optimize the properties of the deposited coatings. After deposition films were annealed in the hydrogen atmosphere in the wide range of temperatures. Structure of coatings was investigated using XRD and SEM. Chemical composition was analyzed using x-ray photo-electron spectroscopy. Sheet conductivity was measured by 4-point probe method. Optical properties of the transparent ZnO-based coatings were studied by the spectroscopy. It was shown that deposition by a DC Arc plasmatron can be used for low-cost production of zinc oxide films with good optical and electrical properties. Sheet resistance of 4 Ohms cm was achieved after the deposition and 30 min annealing in the hydrogen at $350^{\circ}C$. Elevation of the substrate temperature during the deposition process up to $350^{\circ}C$ leads to decreasing of the film's resistance due to rearrangement of the crystalline structure.

• Korean Journal of Crystallography
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• v.6 no.1
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• pp.14-26
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• 1995

The growth mechanism of diamond thin films, deposited by Hot Filament CVD, was investigated through observation of changes in their surface morphology as a function of the substance temperature and deposition time. Amorphous carbon or DLC thin films were deposited at low substrate temperature. Diamond films consisting of square-shaped particles, whose surfaces are (100) planes, were deposited at an intermedate temperature. At high substrate temperatures, diamond films consisting of the particles showing both (100) and (111) plane were deposited. The (100) proferred orientation of the diamond films are believed to be due to a relatively high supersaturation during deposition, and the growth condition for the diamond films having (100) preferred orientation can be applied to the single crystal growth since no twins are generated on the (100) plane. The grain size of the diamond films did not change with increasing temperature and its increasing rate with increasing deposition time was the same irrespective of the substrate temperature. However, the nucleation density increased with substrate temperature and its increasing rate with deposition time was much higher for the films deposited at higher substrate temperature.

• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.37-42
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• 2013

Tristructural-isotropic (TRISO)-coated particles were fabricated by a fluidized-bed chemical vapor deposition (FBCVD) method for use in a very high temperature gas-cooled reactor (VHTR). ZrC as a constituent layer of TRISO coating layers was deposited by a chloride process using $ZrCl_4$ and $CH_4$ source gases in a temperature range of $1400^{\circ}C$ and $1550^{\circ}C$. The change in the microstructure of ZrC depending on the deposition temperature and its effect on the hardness were evaluated. As the deposition temperature increased to $1500^{\circ}C$, the grain size of the ZrC increased and the hardness of the ZrC decreased according to the Hall-Petch relationship. However, at $1550^{\circ}C$, the ZrC layer was highly non-stoichiometric and carbon-rich and did not obey the Hall-Petch relationship in spite of the decrease of the grain size. A considerable amount of pyrolytic carbon at the grain boundaries of the ZrC as well as coarse granular pyrolytic carbon were locally distributed in the ZrC layer deposited at $1550^{\circ}C$. Therefore, the hardness decreased largely due to the formation of a large amount of pyrolytic carbon in the ZrC layer.

• Progress in Superconductivity
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• v.11 no.1
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• pp.62-66
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• 2009

Introduction of proper impurity into $YBa_2Cu_3O_{7-x}$ (YBCO) thin films is an effective way to enhance its flux-pinning properties. We investigate effect of $Y_2O_3$ nanoparticles on the critical current density $J_c$ of the YBCO thin films. The $Y_2O_3$ nanoparticles were created perpendicular to the film surface (parallel with the c-axis) either between YBCO and substrate or on top of YBCO, YBCO/$Y_2O_3$/LAO or $Y_2O_3$/YBCO/STO, by pulsed laser deposition. The deposition temperature of the YBCO films were varied ($780^{\circ}C$ and $800^{\circ}C$) to modify surface morphology of the YBCO films. Surface morphology characterization revealed that the lower deposition temperature of $780^{\circ}C$ created nano-sized holes on the YBCO film surface which may behave as intrinsic pinning centers, while the higher deposition temperature produced much denser and smoother surface. $J_c$ values of the YBCO films with $Y_2O_3$ particles were either remained nearly the same or decreased for the samples in which YBCO is grown at $780^{\circ}C$. On the other hand, $J_c$ values were enhanced for the samples in which YBCO is grown at higher temperature of $800^{\circ}C$. The difference in the effect of $Y_2O_3$ can be explained by the fact that the higher deposition temperature of $800^{\circ}C$ reduces intrinsic pinning centers and $J_c$ is enhanced by introduction of artificial pinning centers in the form of $Y_2O_3$ nanoparticles.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.18-21
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• 2018

We report on the simple preparation method of large-scale structured catalysts by temperature-regulated chemical vapor deposition with a high cell-density ceramic honeycomb monolith. And the feasibility for dry reforming of methane catalysts was evaluated. The NiO/Cordierite (CDR) catalyst was prepared by controlling coating conditions at each temperature step, leading to a conformal deposition of NiO inside the cordierite honeycomb monolith with the cell density of 600 cpsi. The catalytic conversion of $CH_4$ and $CO_2$ for dry reforming of methane were about 83% and 90% with gas hourly space velocity of $10,000h^{-1}$ at $800^{\circ}C$, respectively. As a result, it exhibited that the temperature-regulated chemical vapor deposition method can be expedient for the preparation of large-scale structured catalysts.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.54-54
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• 2018

To optimize the deposition parameters of diamond films, the temperature, pressure, and distance between the filament and the susceptor need to be considered. However, it is difficult to precisely measure and predict the filament and susceptor temperature in relation to the applied power in the hot filament chemical vapor deposition (HFCVD) system. In this study the temperature distribution inside the system was numerically calculated for the applied powers of 12, 14, 16 and 18 kW. The applied power needed to achieve the appropriate temperature at a constant pressure and other conditions was deduced, and applied to actual experimental depositions. The numerical simulation was conducted using the commercial computational fluent dynamics software, ANSYS-FLUENT. To account for radiative heat-transfer in the HFCVD reactor, the discrete ordinate (DO) model was used. The temperatures of the filament surface and the susceptor at different power levels were predicted to be 2512 ~ 2802 K, and 1076 ~ 1198 K, respectively. Based on the numerical calculations, experiments were performed. The simulated temperatures for the filament surface were in good agreement with experimental temperatures measured using a 2-color pyrometer. The results showed that the highest deposition rate and the lowest deposition of non-diamond was obtained at a power of 16 kW.

• Journal of the Korean institute of surface engineering
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• v.56 no.3
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• pp.201-207
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• 2023

Eu³⁺-doped SnO² (SnO²:Eu³⁺) phosphor thin films were grown on quartz substrates by radio-frequency magnetron sputtering. The deposition temperature was varied from 100 to 400 ℃. The X-ray diffraction patterns showed that all the thin films had two mixed phases of SnO₂ and Eu₂Sn₂O₇. The 880 nmthick SnO²:Eu³⁺ thin film grown at 100 ℃ exhibited numerous pebble-shaped particles. The excitation spectra of SnO²:Eu³⁺ thin films consisted of a strong and broad peak at 312 nm in the vicinity from 250 to 350 nm owing to the O^2--Eu3+ charge transfer band, irrespective of deposition temperature. Upon 312 nm excitation, the SnO²:Eu³⁺ thin films showed a main emission peak at 592 nm arising from the ⁵D₀→⁷F₁ transition and a weak 615 nm red band originating from the ⁵D₀→⁷F₂ transition of Eu³⁺. As the deposition temperature increased, the emission intensities of two bands increased rapidly, approached a maximum at 100 ℃, and then decreased slowly at 400 ℃. The thin film deposited at 200 ℃ exhibited a band gap energy of 3.81 eV and an average transmittance of 73.7% in the wavelength range of 500-1100 nm. These results indicate that the luminescent intensity of SnO²:Eu³⁺ thin films can be controlled by changing the deposition temperature.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.90-96
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• 1994

ZnO thin films were deposited using Diethylzinc and $N_{2}O$ gas by plasma enhanced CVD (PECVD) at low substrate temperatures below $300^{\circ}C$. The effect of deposition parameters on the growth rate and the structural properties was determined at various deposition conditions. Crystallized ZnO thin films were successfully deposited even at $150^{\circ}C$ of substrate temperature. Above $200^{\circ}C$ c-axis oriented ZnO thin films, of which a standard deviation of X-ray rocking curve was less than $6^{\circ}$. were deposited on glass substrates. The variation of deposition rate showed different trends depending on substrate temperature and rf-input power. According to the deposition rate behavior as a function of substrate temperature, the transition points were observed resulting from crystallization of ZnO thin films. The activation energies for the deposition of ZnO thin films were 3.1KJ/mol and 1.9KJ/mol for the rf powers of 200W and 250W, respectively.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.361-367
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• 1998

$\alpha$-Sexithiophene ($\alpha$-6T) thin films were deposited by organic molecular beam deposition (OMBD) technique. The $\alpha$-6T was synthesized and purified by the sublimation method. The thin films of the $\alpha$-6T were deposited under various deposition conditions. The effects of deposition rate, substrate temperature, and vacuum pressure on the formation of these films have been studied. The molecular orientation, crystallinity, and surface morphology of $\alpha$-6T films were investigated with angle-resolved UV/visible absorption spectroscopy, X-ray diffractometry (XRD), and atomic force microscopy (AFM). It was found that the crystalline structure of $\alpha$-6T films was monoclinic and independent uppon substrate temperature, deposition rate, and deposition pressure. On the other hand, the $\alpha$-6T molecules in the film deposited at a low deposition rate, higher substrate temperature, and under a high vacuum tended to be aligned perpendicular to the substrate.

• Korean Journal of Materials Research
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• v.33 no.11
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• pp.491-496
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• 2023

As the demand for p-type semiconductors increases, much effort is being put into developing new p-type materials. This demand has led to the development of novel new p-type semiconductors that go beyond existing p-type semiconductors. Copper iodide (CuI) has recently received much attention due to its wide band gap, excellent optical and electrical properties, and low temperature synthesis. However, there are limits to its use as a semiconductor material for thin film transistor devices due to the uncontrolled generation of copper vacancies and excessive hole doping. In this work, p-type CuI semiconductors were fabricated using the chemical vapor deposition (CVD) process for thin-film transistor (TFT) applications. The vacuum process has advantages over conventional solution processes, including conformal coating, large area uniformity, easy thickness control and so on. CuI thin films were fabricated at various deposition temperatures from 150 to 250 ℃ The surface roughness root mean square (RMS) value, which is related to carrier transport, decreases with increasing deposition temperature. Hall effect measurements showed that all fabricated CuI films had p-type behavior and that the Hall mobility decreased with increasing deposition temperature. The CuI TFTs showed no clear on/off because of the high concentration of carriers. By adopting a Zn capping layer, carrier concentrations decreased, leading to clear on and off behavior. Finally, stability tests of the PBS and NBS showed a threshold voltage shift within ±1 V.