• Korean Journal of Materials Research
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• v.5 no.7
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• pp.816-819
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• 1995

(Ba$_{1-x}$ , Sr$_{x}$)TiO/$_3$thin films on Pt/Ti/SiO$_2$/Si substrates were prepared by LP MOCVD(Low Pressure Metal-Organic Chemical Vapor Deposition). The crystalinity of BST deposit had a (100) preferred orientation with increasing deposition temperature due to surface diffusion. BST films deposited at 90$0^{\circ}C$ showed a dielectric constant of 365 and a dissipation factor of 0.052 at a frequency of 100kHz. The chance of capacitance of the films with applied voltage was small, showing paraelectric properties. BST film deposited at 90$0^{\circ}C$ had a charge storage density of 60 fc/${\mu}{\textrm}{m}$$^2$at a field of 0.2MV/cm and the leakage current density of 20 nA/$\textrm{cm}^2$ at a field of 0.15 MV/cm.cm.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.141-141
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• 2010

The effect of thermal anneal on the characteristics of structural properties and the enhancement of luminescence and photovoltaic (PV) characteristics of silicon-rich silicon-nitride films were investigated. By using an ultra high vacuum ion beam sputtering deposition, B-doped silicon-rich silicon-nitride (SRSN) thin films, with excess silicon content of 15 at. %, on P-doped (n-type) Si substrate was fabricated, sputtering a highly B doped Si wafer with a BN chip by N plasma. In order to examine the influence of thermal anneal, films were then annealed at different temperature up to $1100^{\circ}C$ under $N_2$ environment. Raman, X-ray diffraction, and X-ray photoemission spectroscopy did not show any reliable evidence of amorphous or crystalline Si clusters allowing us concluding that nearly no Si nano-cluster could be formed through the precipitation of excess Si from SRSN matrix during thermal anneal. Instead, results of Fourier transform infrared and X-ray photoemission spectroscopy clearly indicated that defective, amorphous Si-N matrix of films was changed to be well-ordered thanks to high temperature anneal. The measurement of spectral ellipsometry in UV-visible range was carried out and we found that the optical absorption edge of film was shifted to higher energy as the anneal temperature increased as the results of thermal anneal induced formation of $Si_3N_4$-like matrix. These are consistent with the observation that higher visible photoluminescence, which is likely due to the presence of Si-N bonds, from anneals at higher temperature. Based on these films, PV cells were fabricated by the formation of front/back metal electrodes. For all cells, typical I-V characteristic of p-n diode junction was observed. We also tried to measure PV properties using a solar-simulator and confirmed successful operation of PV devices. Carrier transport mechanism depending on anneal temperature and the implication of PV cells based on SRSN films were also discussed.

• Journal of the Korean Vacuum Society
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• v.6 no.2
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• pp.143-150
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• 1997

In this study, doffusion barrier properties of 1000 $\AA$ thick molybdenum compound(Mo, Mo-N, $MoSi_2$, Mo-Si-N) films were investigated using sheet resistance measurement, X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Scanning electron mircoscopy(SEM), and Rutherford back-scattering spectrometry(RBS). Each barrier material was deposited by the dc magnetron sputtering and annealed at 300-$800^{\circ}C$ for 30 min in vacuum. Mo and MoSi2 barrier were faied at low temperatures due to Cu diffusion through grain boundaries and defects in Mo thin film and the reaction of Cu with Si within $MoSi_2$, respectively. A failure temperature could be raised to $650^{\circ}C$-30 min in the Mo barrier system and to $700^{\circ}C$-30 min in the Mo-silicide system by replacing Mo and $MoSi_2$ with Mo-N and Mo-Si-N, respectively. The crystallization temperature in the Mo-silicide film was raised by the addition of $N_2$. It is considered that not only the $N_2$, stuffing effect but also the variation of crystallization temperature affects the reaction of Cu with Si within Mo-silicide. It is found that Mo-Si-N is the more effective barrier than Mo, $MoSi_2$, or Mo-N to copper penetraion preventing Cu reaction with the substrate for $30^{\circ}C$min at a temperature higher than $650^{\circ}C$.

• Electrical & Electronic Materials
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• v.10 no.7
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• pp.706-712
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• 1997

AlN(Aluminium Nitride) thin films were prepared using by RF sputtering method on the Si(100) and Si(111) substrates as the parameters of the substrate temperature, RF power, sputtering duration and the $N_2$/Ar ratio and investigated by X-ray diffraction, IR spectrometry, n&k analyzer. For the Si(100) substrate, the AlN thin films of (101) orientation were obtained under the conditions of room temperature and the nitrogen of 60 vol.%. For the Si(111) substrate, the (002) AlN thin films were obtained under the nitrogen of 100 vol.%. In case of the thin film prepared in the condition of above 60 vol.% of the nitrogen, the average value of the surface roughness of the film was 151$\AA$. From the changes of the half widths of E$_1$[TO] phonon bands at the wavenumber of 680$cm^{-1}$ /, it were compared of the crystallinities of the films which were grown under the different conditions. The thicknesses of AlN films were decreased dramatically in the region of the nitrogen of 40~60 vol.%. Its due to the nitridation of the Al target surface and getting low of the sputtering yield by the $N_2$/Ar ratio being increased.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.26-26
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• 2000

High quality epitaxial Y2O3 thin films were prepared on Si(111) and (001) substaretes by using ion beam assisted deposition. As a substrate, clean and chemically oxidized Si wafers were used and the effects of surface state on the film crystallinity were investigated. The crystalline quality of the films were estimated by x-ray scattering, rutherford backscattering spectroscopy/channeling, and high-resolution transmission electron microscopy (HRTEM). The interaction between Y and Si atoms interfere the nucleation of Y2O3 at the initial growth stage, it could be suppressed by the interface SiO2 layer. Therefore, SiO2 layer of the 4-6 layers, which have been known for hindering the crystal growth, could rather enhance the nucleation of the Y2O3 , and the high quality epitaxial film could be grown successfully. Electrical properties of Y2O3 films on Si(001) were measured by C-V and I-V, which revealed that the oxide trap charge density of the film was 1.8$\times$10-8C/$\textrm{cm}^2$ and the breakdown field strength was about 10MV/cm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.10
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• pp.1049-1054
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• 2012

Continued advancements in organic materials have led to the development of organic devices that are thin, flexible, and lightweight and that can potentially be used as low-cost energy-conversion devices. While these devices have many advantages, the environmentally induced degradation of the active materials and the low-work-function electrodes remain a valid concern. Hence, many vacuum deposition processes have been applied to develop low-permeation barrier coatings. In this work, we present the results pertaining to the developed thin-film encapsulation. Multilayer encapsulation involves the use of $SiO_x$ or $SiN_x$ with parylene. The effective water vapor transmission rates were investigated using a Ca-corrosion test. The integration of the developed barrier layers was demonstrated by encapsulating pentacene/$C_{60}$ solar cells, and the results are presented.

• Solar Energy
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• v.11 no.1
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• pp.41-49
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• 1991

In this study, the (P)SiC/(N)Si solar cell is fabricated by the vacuum evaporation method with the substrate temperature at about $200{\pm}5[5^{\circ}C]$ and its characteristics are investigated. The optimal thickness of $1.2[{\mu}m]$ of SiC film is derived from the relation between film thickness and conversion efficiency. The characteristics of solar cells are improved by the annealing. The optimum annealing temperature and duration are $420[^{\circ}C]$ and 12[min], respectively it is shown that the peak values of spectral response are shifted to the long wavelength region with increasing the annealing temperature. The X-ray diffraction patterns and the scanning electron micrographs show the grain grow thin SiC film as the annealing temperature and time is increased. The best conversion efficiency is 11.7[%] for a $2.5{\times}1[cm^2]$ cell.

• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.137-143
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• 2010

Oxide semiconductors Thin-film transistors are an exemplified one owing to its excellent ambient stability and optical transparency. In particular zinc oxide (ZnO) has been reported because It has stability in air, a high electron mobility, transparency and low light sensitivity, compared to any other materials. For this reasons, ZnO TFTs have been studied actively. Furthermore, we expected that would be satisfy the demands of flexible display in new generation. In order to do that, ZnO TFTs must be fabricated that flexible substrate can sustain operating temperature. So, In this paper we have studied low-temperature process of zinc oxide(ZnO) thin-film transistors (TFTs) based on silicon nitride ($SiN_x$)/cross-linked poly-vinylphenol (C-PVP) as gate dielectric. TFTs based on oxide fabricated by Low-temperature process were similar to electrical characteristics in comparison to conventional TFTs. These results were in comparison to device with $SiN_x$/low-temperature C-PVP or $SiN_x$/conventional C-PVP. The ZnO TFTs fabricated by low-temperature process exhibited a field-effect mobility of $0.205\;cm^2/Vs$, a thresholdvoltage of 13.56 V and an on/off ratio of $5.73{\times}10^6$. As a result, We applied experimental for flexible PET substrate and showed that can be used to ZnO TFTs for flexible application.

• Solar Energy
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• v.12 no.2
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• pp.62-78
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• 1992

The solar cells of $ITO_{(n)}/Si_{(p)}$, which are ITO thin films deposited and heated on Si wafer 190[$^{\circ}C$], were fabricated by two source vaccum deposition method, and their electrical properties were investigated. Its maximum output is obtained when the com- position of the thin film consist of indium oxide 91[mole %] and thin oxide 9[mole %]. The cell characteristics can be improved by annealing but are deteriorated at temperature above 600[$^{\circ}C$] for longer than 15[min]. Also, we investigated the spectral response with short circuit current of the cells and found that the increasing of the annealing caused the peak shifted to the long wavelength region. And by experiment of the X-ray diffraction, it is shown to grow the grains of the thin film with increasment of annealing temperature. The test results from the $ITO_{(n)}/Si_{(p)}$ solar cell are as follows. short circuit current : Isc= 31 $[mW/cm^2]$ open circuit voltage : Voc= 460[mV] fill factor : FF=0.71 conversion efficiency : ${\eta}$=11[%]. under the solar energy illumination of $100[mW/cm^2]$.

• Nuclear Engineering and Technology
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• v.40 no.3
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• pp.233-238
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• 2008

This study investigates the surface modification of a Hastelloy X plate and diffusion bonding in the assembly of surface modified plates. These types of plates are involved in the key processes in the fabrication of a process heat exchanger (PHE) for a $SO_3$ decomposer. Strong adhesion of a SiC film deposited onto Hastelloy X can be achieved by a thin SiC film deposition and a subsequent N ion beam bombardment followed by an additional deposition of a thicker film that prevents the Hastelloy X surface from becoming exposed to a corrosive environment through the pores. This process not only produces higher corrosion resistance as proved by electrolytic etching but also exhibits higher endurance against thermal stress above 9$900^{\circ}C$. A process for a good bonding between Hastelloy X sheets, which is essential for a good heat exchanger, was developed by diffusion bonding. The diffusion bonding was done by mechanically clamping the sheets under a heat treatment at $900^{\circ}C$. When the clamping jig consisted of materials with a thermal expansion coefficient that was equal to or less than that of the Hastelloy X, sound bonding was achieved.