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

• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.56-61
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• 1997

Lead zirconate titanate (PZT) thin fills were deposited onto the Pt/Ti/SiO2/Si substrate by the pulsed laser deposition with the second harmonic wavelength (532 nm) of Nd:YAG laser. In order to determine the optimum conditions for the film deposition, the phase of the films were investigated as functions of ambient oxygen pressure, substrate temperature, and laser fluence. Also the chemical composition analysis was conducted for the PZT films deposited under various ambient oxygen pressure. When the distance between substrate and bulk PZT target is set to 20 mm, the optimum conditions have been determined to be 3 torr of oxygen pressure, 1.5 J/cm2 of laser fluence, and 823-848(±10) K range of substrate temperature. At these conditions, perovskite phase PZT films were obtained on platinized silicon. The chemical composition of the films is very similar to that of PZT bulk target. The physical structure of the deposited films analyzed by scanning electron microscopy shows a columnar morphology perpendicular to the substrate surface. Capacitance-Voltage hysteresis loop measurements show also a typical characteristics of ferroelectric thin film. The dielectric constant is found to be 528 for the 0.48 μm thickness of PZT thin film.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.44-44
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• 2003

Growth mechanism of carbon nanotubes(CNTs) synthesized by chemical vapor deposition is abided by two growth modes. These growth modes are classified by the position of activated catalytic metal particle in the CNTs. Growth mode can be also affected by interaction between substrate and catalytic metal and induced energy such as thermal and plasma. We studied the reaction of catalytic metal to the substrate and growth mode of CNTs. Various substrates such as Si(100), graphite plate, coming glass, sapphire and AAO membrane are used to study the relation between catalytic metal and substrate in the synthesis of CNTs. For catalytic metal, thin film was deposited on various substrate via sputtering technique with a thickness of ∼20nm and magnetic fluids with none-sized particles were dispersed on AAO membrane. After laying process on AAO membrane, it was dried at 80$^{\circ}C$ for 8 hour. Synthesizing of CNTs was carried out at 900$^{\circ}C$ in NH3/C2H2 mixture gases flow for 10minutes.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.6
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• pp.118-127
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• 2009

Effect of a finite square substrate plane on the radiation characteristics of a microstrip patch antenna is investigated. Excellent agreements between the simulation and measured results on the radiation characteristics of patch antennas for various square substrate thicknesses and sizes are obtained. The effect of a square substrate plane on the resonant frequency and bandwidth is small, while that on the radiation pattern is large. As the substrate thickness increases, the variations of the gain of the broadside radiation, the direction of the maximum radiation, and the radiation pattern increase for the variation of a substrate size. The maximum gain difference between the broadside radiation and back radiation and the large gain of broadside radiation are obtained when the length of a side of a square substrate plane is $0.8\;{\lambda}_0$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.428-435
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• 2002

Pyroelectric $Pb(Zr_{0.3}Ti_{0.7})O_3$ (PZT30/70) thin film IR detectors has been fabricated and characterised. The PZT30/70 thin film was deposited onto $Pt/Ti/Si_3N_4/SiO_2/Si$ substrate by the sol-gel process. Four different substrate conditions were studied for their effects on the pyroelectric responses of the IR detectors. The substrate conditions were the combinations of the Si etching and the Pt/Ti patterning. In the Si etched substrate, the $Si_3N_4/SiO_2$ composite layer was used as silicon etch-stop, and was used as the membrane to support the PZT pyroelectric film element as well. The measured pyroelectric current and voltage responses of detectors fabricated on the micro-machined thin $Si_3N_4/SiO_2$ membrane were two orders higher than those of the detectors on the bulk-silicon. For detectors on the membrane substrate, the Pt/Ti patterned detectors showed a 2-times higher pyroelectric response than that of not-patterned detectors. On the other hand, the pyroelectric response of the detectors on the not-etched Si substrate was almost the same, regardless of the Pt/Ti patterning. It was also found that the rise time strongly depended on the substrate thickness: the thicker the substrate was, the longer the rise-time.

• Journal of the Korean Vacuum Society
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• v.10 no.4
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• pp.387-395
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• 2001

The elastic modulus and the structural evolution were examined with the film thickness in polymeric, hard, graphitic diamond-like carbon (DLC) films. The DLC films used in the present study were prepared by radio frequency plasma assisted chemical vapor deposition (r.f.-PACVD) from $C_6H_6\;and\;CH_4$ gas. Elastic modulus of very thin DLC film was measured by free overhang method. This method has an advantage over the other methods. Because the substrate was removed by etching technique, the measured value is not affected by the mechanical property of the substrate. The structural evolution was investigated by the G-peak position of the Raman spectrum. The polymeric and graphitic films exhibited the decreased elastic modulus with decreasing film thickness. In polymeric films, the reason was that more polymeric film had been deposited in the initial stage of the film growth and in graphitic film more graphic films which had been deposited in the initial stage decreased the elastic modulus. The G-peak position of the Raman spectrum confirmed this result. On the other hand, the hard film showed the constant elastic modulus regardless to the film thickness. The structural change was not observed in this range of the film thickness.

• Transactions on Electrical and Electronic Materials
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• v.15 no.4
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• pp.198-200
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• 2014

100 nm thick Ga doped ZnO (GZO) thin films were deposited with RF magnetron sputtering on polyethylene terephthalate (PET) and ZnO coated PET substrate and then the effect of the ZnO thickness on the optical and electrical properties of the GZO films was investigated. GZO single layer films had an optical transmittance of 83.7% in the visible wavelength region and a sheet resistance of $2.41{\Omega}/{\square}$, while the optical and electrical properties of the GZO/ZnO bi-layered films were influenced by the thickness of the ZnO buffer layer. GZO films with a 20 nm thick ZnO buffer layer showed a lower sheet resistance of $1.45{\Omega}/{\square}$ and an optical transmittance of 85.9%. As the thickness of ZnO buffer layer in GZO/ZnO bi-layered films increased, both the conductivity and optical transmittance in the visible wavelength region were increased. Based on the figure of merit (FOM), it can be concluded that the ZnO buffer layer effectively increases the optical and electrical performance of GZO films as a transparent and conducting electrode without intentional substrate heating or a post deposition annealing process.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.558-565
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• 2020

AZO thin films are grown on a p-Si(111) substrate by RF magnetron sputtering. The characteristics of various thicknesses and heat treatment conditions are investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Hall effect and room-temperature photoluminescence (PL) measurements. The substrate temperature and the RF power during growth are kept constant at 400 ℃ and 200 W, respectively. AZO films are grown with a preferred orientation along the c-axis. As the thickness and the heat treatment temperature increases, the length of the c-axis decreases as Al³⁺ ions of relatively small ion radius are substituted for Zn²⁺ ions. At room temperature, the PL spectrum is separated into an NBE emission peak around 3.2 eV and a violet regions peak around 2.95 eV with increasing thickness, and the PL emission peak of 300 nm is red-shifted with increasing annealing temperature. In the XPS measurement, the peak intensity of Al_2p and O_ll increases with increasing annealing temperature. The AZO thin film of 100 nm thickness shows values of 6.5 × 10¹⁹ cm^-3 of carrier concentration, 8.4 cm^-2/V·s of mobility and 1.2 × 10^-2 Ω·cm electrical resistivity. As the thickness of the thin film increases, the carrier concentration and the mobility increase, resulting in the decrease of resistivity. With the carrier concentration, mobility decreases when the heat treatment temperature increases more than 500 ℃.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.105-110
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• 2009

IZO thin films have been deposited on poly(ethylene terephthalate) flexible substrate under varying radio frequency (rf) power, process pressure and thickness of IZO films using rf magnetron sputtering under $Ar/O_2$ gas mix. As the process pressure increased, the deposition rate was slightly increased and the transmittance showed little change, but the resistivity was increased. With increasing rf power, the great increase in deposition rate was observed but the transmittance showed a slight change only, and the resistivity was decreased. In addition, an attempt was made to find the optimal thickness of IZO films under varying the thickness of IZO films at the process conditions of 1 mTorr pressure and 90 W rf power, which showed lowest resistivity. IZO thin films with the thickness of $1,500{\AA}$ showed lowest resistivity and also showed highest transmittance around the wavelength zone of the maximum absorption. The power conversion efficiency of solar cells fabricated using various transparent electrodes with different thicknesses were measured and the solar cell with IZO electrode of $1,500{\AA}$ showed the maximum conversion-efficiency of 2.88 %.

• Tribology and Lubricants
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• v.32 no.4
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• pp.125-131
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• 2016

In recent years, thick ta-C coating has attracted considerable interest owing to its existing and potential commercial importance in applications such as automobile accessories, drills, and gears. The thickness of the ta-C coating is an important parameter in these applications. However, the biggest problems are achieving efficient coating and uniformity over a large area with high-speed deposition. Feasibility is confirmed for the ta-C coating thickness of up to 9.0 µm (coating speed: 3.0 µm/h, fixed substrate) using a single FCVA cathode. The thickness was determined using multiple coating cycles that were controlled using substrate temperature and residual stresses. In the present research, we have designed a coating system using FCVA plasma and produced enhanced thick ta-C coating. The system uses a specialized magnetic field configuration with stabilized DC arc plasma discharge during deposition. To achieve quality that is acceptable for use in automobile accessories, the magnetic field, T-type filters, and 10 pieces of a multi-cathode are used to demonstrate the deposition of the thick ta-C coating. The results of coating performance indicate that uniformity is ±7.6 , deposited area is 400 mm, and the thickness of the ta-C coating is up to 5.0 µm (coating speed: 0.3 µm/h, revolution and rotation). The hardness of the coating ranges from 30 to 59 GPa, and the adhesion strength level (HF1) ranges from 20 to 60 N, depending on the ta-C coating.