• The Korean Journal of Ceramics
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• v.3 no.4
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• pp.274-278
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• 1997

(Ba, Sr) TiO$_3$(BST) thin films were prepared on RuO$_2$/Si substrates by rf magnetron sputtering and annealing was followed at temperatures ranging from 550 to 80$0^{\circ}C$ in $N_2$or $O_2$atmosphere. The effects of annealing conditions on the properties of BST film deposited on RuO$_2$bottom electrodes were investigated. It was found that the crystallinity. surface roughness, and grain size of BST films vary with the annealing temperature but they are not dependent upon the annealing atmosphere. The flat region in the current-voltage (I-V) curves of BST capacitors shortened with increasing annealing temperature under both atmospheres. This is believed to be due to the lowering of potential barrier caused by unstable interface and the increase of charge The shortening of the flat region by $O_2$annealing was more severe than that by $N_2$-annealing. As a result, there was no flat region when the films were annealed at 700 and 80$0^{\circ}C$ in $O_2$atmosphere. The dielectric properties of BST films were improved by annealing in either atmosphere. however, a degradation with frequency was observed when the films were annealed at relatively high temperature under $O_2$atmosphere.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.177-184
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• 1996

We adopted the $Pt/SiO_{2}/Si$ and the $Ir/SiO_{2}/Si$ substrates of which buffer layer is $PbTiO_{3}$ to improve electrode and interfacial properties of PZT thin film deposited by reactive sputtering method using metal target in this study. We got PZT thin film to have highly oriented(100) structure and good crystallinity using buffer layer in Pt bottom-electrode, though randomly oriented PZT thin film was obtained without buffer layer. Although great improvement of PZT phase formation on Ir bottom-electrode with buffer layer was not observed, we observed the increase of remennant polarization and the decrease of coercive field compared with properties of PZT thin films on the Pt bottom-electrode. So we got the results of the increase of dielectric constant using buffer layer on fabrication of PZT thin film and the better dielectric properties in PZT thin film using Ir bottom-electrode compared with that using Pt bottom-electrode.

• Journal of the Korean Magnetics Society
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• v.25 no.2
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• pp.47-51
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• 2015

To achieve a high tunneling magneto resistance (TMR) of sputtered magnetic tunnel junctions (MTJs) with an MgO barrier, the annealing process is indispensable. The structural and compositional changes as consequences of the annealing greatly affect the spin-dependent transport properties of MTJs. Higher TMR could be obtained for MTJs annealed at higher annealing temperature. The diffusion of Ru, Mn and/or Ta in the MTJs may occur during annealing process, which is known to be detrimental to spin-dependent tunneling effect. The rapid thermal annealing (RTA) process was used for annealing the MTJs with synthetic antiferromagnets. To suppress the diffusion of Mn, Ru and/or Ta in the MTJs, the process time and temperature of RTA were minutely controlled.

• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.7-13
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• 1995

A new FET type semiconductor pressure sensor (PSFET : pressure sensitive field effect transistor) was fabricated and its operational characteristics were investigated. A ZnO thin film as a piezoelectric layer, $5000{\AA}$ thick, was deposited on a gate oxide of FET by RF magnetron sputtering. The deposition conditions to obtain a c-axis poling structure were substrate temperature of $300^{\circ}C$, RF power of 140watt, and working pressure of 5mtorr in Ar ambience. The fabricated PSFET device showed good linearity and stability in the applied pressure range($1{\times}10^{5}\;Pa{\sim}4{\times}10^{5}\;Pa$).

• Journal of Sensor Science and Technology
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• v.6 no.2
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• pp.81-86
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• 1997

Platinum thin films were deposited on $SiO_{2}/Si$ and $Al_{2}O_{3}$ substrates by DC magnetron sputtering for RTD (resistance thermometer devices) temperature sensors. The resistivity and sheet resistivity of these films were decreased with increasing the annealing temperature and time. We made Pt resistance pattern on $Al_{2}O_{3}$ substrate by lift-off method and fabricated Pt-RTD temperature sensors by using W-wire, silver epoxy and SOG(spin-on-glass). In the temperature range of $25{\sim}400^{\circ}C$, we investigated TCR(temperature coefficient of resistance) and resistance ratio of Pt-RTD temperature sensors. TCR values were increased with increasing the annealing temperature, time and the thickness of Pt thin films. Resistance values were varied linearly within the range of measurement temperature. At annealing temperature of $1000^{\circ}C$, time of 240min and thin film thickness of $1{\mu}m$, we obtained TCR value of $3825ppm/^{\circ}C$ close to the Pt bulk value.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.251-255
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• 2009

Nanocomposites based on coupling $TiO_2$ matrix with nanosized noble metals (Pt,Au) particles exhibited promising photoelectrode properties. The $M/TiO_2$ (M=Pt,Au) nanocomposite thin films were deposited on quartz and ITO glass substrates using a co-sputtering method. $TiO_2$ in rutile form is the dominant crystalline phase for as-deposited nanocomposite films. Along with heat treatment up to $600^{\circ}C$, XRD peaks of the rutile phase as well as those of noble metal increased in intensity and decreased in width, indicating the growth of crystallites. The anodic photocurrents of $M/TiO_2$ (M=Au,Pt) thin films were observed not only in the UV range but also in the visible light range. The photocurrent of the nanocomnosite films extended to the visible light region by dispersion of nano-sized noble metal in the $TiO_2$ matrix.

• Applied Science and Convergence Technology
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• v.23 no.6
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• pp.309-316
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• 2014

A large particle accelerator requires an ultrahigh vacuum (UHV) system of average pressure under $1{\times}10^{-7}$ Pa for mitigating the impact of beam scattering from the residual gas molecules. The surface inside the beam ducts should be controlled with an extremely low thermal outgassing rate under $1{\times}10^{-9}Pa{\cdot}m^3/(s{\cdot}m^2)$ for the sake of the insufficient pumping speed. To fulfil the requirements, the aluminum alloys were adopted as the materials of the beam ducts for large accelerator that thanks to the good features of higher thermal conductivity, non-radioactivity, non-magnetism, precise machining capability, et al. To put the aluminum into the large accelerator vacuum systems, several key technologies have been developed will be introduced. The concepts contain the precise computer numerical control (CNC) machining process for the large aluminum ducts and parts in pure alcohol and in an oil-free environment, surface cleaning with ozonized water, stringent welding process control manually or automatically to form a large sector of aluminum ducts, ex-situ baking process to reach UHV and sealed for transportation and installation, UHV pumping with the sputtering ion pumps and the non-evaporable getters (NEG), et al. The developed UHV technologies have been applied to the 3 GeV Taiwan Photon Source (TPS) and revealed good results as the expectation. The problems of leakage encountered during the assembling were most associated with the vacuum baking which result in the consequent trouble shootings and more times of baking. Then the installation of the well-sealed UHV systems is recommended.

• Korean Journal of Materials Research
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• v.21 no.9
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• pp.491-496
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• 2011

Transparent conducting oxides (TCOs) used in the antireflection layer and current spreading layer of heterojunction solar cells should have excellent optical and electrical properties. Furthermore, TCOs need a high work function over 5.2 eV to prevent the effect of emitter band-bending caused by the difference in work function between emitter and TCOs. Sn-doped $In_2O_3$ (ITO) film is a highly promising material as a TCO due to its excellent optical and electrical properties. However, ITO films have a low work function of about 4.8 eV. This low work function of ITO films leads to deterioration of the conversion efficiency of solar cells. In this work, ITO films with various Zn contents of 0, 6.9, 12.7, 28.8, and 36.6 at.% were fabricated by a co-sputtering method using ITO and AZO targets at room temperature. The optical and electrical properties of Zn-doped ITO thin films were analyzed. Then, silicon heterojunction solar cells with these films were fabricated. The 12.7 at% Zn-doped ITO films show the highest hall mobility of 35.71 $cm^2$/Vsec. With increasing Zn content over 12.7, the hall mobility decreases. Although a small addition of Zn content increased the work function, further addition of Zn content over 12.7 at.% led to decreasing electrical properties because of the decrease in the carrier concentration and hall mobility. Silicon heterojunction solar cells with 12.7 at% Zn-doped ITO thin films showed the highest conversion efficiency of 15.8%.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.862-868
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• 1996

Cadmium sulfide is commonly used as the window material for thin film solar cells, and can be prepared by several techniques such as sputtering, spray pyrolysis, close spaced sublimation (CSS), thermal evaporation, solution growth methods, etc. In this study, CdS films were deposited by thermal evaporation, close spaced sublimation, and solution growth methods, respectively, and the effects of the methods on physical properties of polycrystalline CdS deposited on ITO/glass were investigated. Also, the effects of variously prepared CdS thin films on the physical properties of CdTe deposited on the CdS were investigated. The thickness of polycrystalline CdS films was maintained at $0.3\mu\textrm{m}$ except for the solution grown CdS when $0.2\mu\textrm{m}$ thick CdS was deposited. After the deposition, all the samples were annealed at $400^{\circ}C$ or $500^{\circ}C$ in H2 atmosphere. To investigate physical properties of the deposited and annealed CdS thin films, UV-VIS spectro-photometry, X-ray diffractometry (XRD), and Auger electron spectroscopy (AES), and cross sectional transmission electron microscopy(XTEM) were used to analyze grain size, crystal structure, preferred orientation, optical properties, etc. The annealed CdS showed the bandedge transition at 510nm and the optical transmittance high than 80% for all of the variously deposited films. XRD results showed that CdS thin films variously deposited and annealed had the same hexagonal structures, however, showed different preferred orientations. CSS grown CdS had [103] preferred orientation, thermally evaporated CdS had [002], and CdS grown by the solution growth had no preferred orientation. The largest grain size was obtained for the CSS grown CdS while the least grain size was obtained for the solution grown CdS. Some of the physical properties of CdTe deposited on the CdS thin film such as grain size at the junction and grain orientation were affected by the physical properties of CdS thin films.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.683-690
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• 1996

In this study, the diffusion barrier properties of $1000 \AA$ thick molybdenum compounds (Mo, Mo-N, $MoSi_2$, Mo-Si-N) were investigated using sheet resistance measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Rutherford backscattering spectrometry (RBS). Each barrier material was deposited by the dc magnetron sputtering, and annealed at 300-$800^{\circ}C$ for 30min in vacuum. Mo and $MoSi_2$ barrier were failed at low temperature due to Cu diffusion through grain bound-aries and defects of Mo thin film and the reaction of Cu with Si within $MoSi_2$ respectively. A failure temperature could be raised to $650^{\circ}C$-30min in the Mo barrier system and to $700^{\circ}C$-30min 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, stuffing effect but also the variation of crystallization temperature affects the reaction of Cu with Si within Mo-silicide. It was found that Mo-Si-N is more effective barrier than Mo, $MoSi_2$, or Mo-N to copper penetration preventing Cu reaction with the substrate for 30min at a temperature higher than $650^{\circ}C$.