• The Korean Journal of Ceramics
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• v.3 no.3
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• pp.187-190
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• 1997

The aluminum-magnesium (Al-Mg) aklloys have been proved to be an effective solvent for synthesis of cubic-phase boron nitride (cBN) from hexagonal-phase boron nitride (hBN) at the conditions of high pressures and high temperatures (HP/HT). Various kinds of hBN powders having different crystallinity have been tested for cBN synthesis with Al-Mg solvents. The conversion ratio from hBN to cBN and the shape of synthesized cBN crystals appeared to be affected strongly by chemical composition and added amount of Al-Mg solvents as well as crystallinity of BN powders. As the magnesium content increased in the Al-Mg solvents, the conversion ratio increased and the size of cBN crystals became larger. The crystal facets developed well in the specimens with solvents having high Mg content. It was observed that a hBNlongrightarrowcBN transformation occurred more easily in the specimens having well crystallized hBN powders. Amorphous BN having much $B_2O_3$ impurity exhibited a low threshold temperature for transformation to cBN, which was attributed to crystallization of amorphous BN to well crystallized hBN prior to transformation into cBN with help of $B_2O_3$.

• Journal of Surface Science and Engineering
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• v.43 no.1
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• pp.7-11
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• 2010

Solid phase crystallization (SPC) is a simple method in producing a polycrystalline phase by annealing amorphous silicon (a-Si) in a furnace environment. Main motivation of the crystallization technique is to fabricate low temperature polycrystalline silicon thin film transistors (LTPS-TFTs) on a thermally susceptible glass substrate. Studies on SPC have been naturally focused to the low temperature regime. Recently, fabrication of polycrystalline silicon (poly-Si) TFT circuits from a high temperature polycrystalline silicon process on steel foil substrates was reported. Solid phase crystallization of a-Si films proceeds by nucleation and growth. After nucleation polycrystalline phase is propagated via twin mediated growth mechanism. Elliptically shaped grains, therefore, contain intra-granular defects such as micro-twins. Both the intra-granular and the inter-granular defects reflect the crystallinity of SPC poly-Si. Crystallinity and SPC kinetics of high temperatures were compared to those of low temperatures using Raman analysis newly proposed in this study.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.8
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• pp.616-621
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• 2011

In this paper, CdS thin films, which were widely used window layer of the CdTe and the Cu(In,Ga)$Se_2$ thin film solar cell, were grown by chemical bath deposition, and effects of pH of reaction solution on the structural and optical properties were investigated. For pH<10.5, as the pH of reaction solution was higher, the deposition rate of CdS films was increased by improving ion-by-ion reaction in the substrate surface and the crystallinity of the films was improved. However, when the pH was higher than 10.5, the deposition rate was decreased because of smaller $Cd^{2+}$ ion concentration in the reaction solution. Also, the crystallinity of the films were deteriorated. The CdS films deposited at lower pH showed poor optical transmittance due to adsorbed colloidal particles, while the transmittance was improved for higher pH.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.4
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• pp.145-150
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• 2004

We have investigated the structural, electrical and optical properties of Al-doped ZnO (AZO) thin films grown on glass substrate by pulsed DC magnetron sputtering as functions of pulse frequency and substrate temperature. A highly c-axis oriented AZO thin film is grown in perpendicular to the substrate when pulse frequency of 30 kHz and substrate temperature of $400^{\circ}C$ was applied. Under this optimized growth condition, the resistivity of AZO thin films exhibited $7.40\times 10^{-4}\Omega \textrm{cm}$. This indicated that the decrease of film resistivity resulted from the improvement of film crystallinity. The optical transmittance spectra of the films showed a very high transmittance of 85∼90 % in the visible wavelength region and exhibited the absorption edge of about 350 nm. The results show the potential application for transparent conductivity oxide (TCO) thin films.

• Journal of Sensor Science and Technology
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• v.15 no.2
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• pp.84-89
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• 2006

Highly concentrated p-type ZnO thin films can be obtained by doping of N, P and As elements. In this study, undoped ZnO buffer layers were prepared on a (0001) sapphire substrate by a ultra high vaccum pulsed laser deposition(UHV-PLD) method. ZnO buffer layers were deposited with various deposition temperature($400{\sim}700^{\circ}C$) at 350 mtorr of oxygen working pressure. Arsenic doped(1 wt%) ZnO thin films were deposited on the ZnO buffer layers by UHV-PLD. Crystallinity of the samples were evaluated by X-ray diffractometer and scanning electron microscopy. Optical, electrical properties of the ZnO thin films were estimated by photoluminescence(PL) and Hall measurements. The optimal condition of the undoped ZnO buffer layer for the deposition of As-doped ZnO thin films was at $600^{\circ}C$ of deposition temperature.

• Journal of the Korean Vacuum Society
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• v.13 no.1
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• pp.29-33
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• 2004

In this paper, we investigated the ultra-low temperature(<$150^{\circ}C$) polycrystalline silicon film on plastic substrate application using RF-magnetron sputtering and excimer laser annealing. Amorphous silicon films were deposited using Ar/He mixture gas at $120^{\circ}C$ and in-film argon concentration was less than 2%, which was measured to Rutherford Backscattering Spectrometry. At energy density 320mJ/$\textrm{cm}^2$, RMS roughness was 267$\AA$ and UV crystallinity was 62%. The grain size varies from 50nm to 100nm after excimer laser irradiation.

• Journal of Sensor Science and Technology
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• v.11 no.6
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• pp.371-377
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• 2002

$Y_2O_3:Eu^{3+}$ and Li-doped $Y_2O_3:Eu^{3+}$ thin films have been grown on sapphire substrates using a pulsed laser deposition technique. The thin film phosphors were deposited at a substrate temperature of $600^{\circ}C$ under the oxygen pressure of 100, 200 and 300 mTorr. The films grown under different deposition conditions have been characterized using microstructural and luminescent measurements. The crystallinity and photoluminescence (PL) of the films are highly dependent on the oxygen pressure. The PL brightness data obtained from $Y_2O_3:Eu^{3+}$ films grown under optimized conditions have indicated that sapphire is one of the most promising substrate for the growth of high quality $Y_2O_3:Eu^{3+}$ thin film red phosphor. In particular, the incorporation of $Li^{+}$ ions into $Y_2O_3$ lattice could induce a remarkable increase of PL. The highest emission intensity was observed with LiF-doped $Y_{1.84}Li_{0.08}Eu_{0.08}O_3(Y_2O_3LiEu)$, whose brightness was increased by a factor of 2.7 in comparison with that of $Y_2O_3:Eu^{3+}$ films. This phosphor may promise for application to the flat panel displays.

• Journal of the Korean Vacuum Society
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• v.16 no.3
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• pp.205-209
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• 2007

ZnO thin films were deposited on a Si wafer and a soda lime glass using atomic layer deposition(ALD). The substrate temperature were between $130^{\circ}C{\sim}150^{\circ}C$. The deposition rate of the ZnO film was measured to be $2.72{\AA}$ per cycle. The films were analyzed using field emission scanning electron microscopy(FESEM), X-ray diffractometer(XRD), and Auger electron spectroscopy(AES). Impurity-free ZnO thin films were obtained and the crystallinity was found to be dependant upon the substrate temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.857-860
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• 2002

The material that is both conductive in electricity and transparent to the visible-ray is called transparent conducting thin film. It has many field of application such as solar cell, liquid crystal display, transparent electrical heater, selective optical filter, and a optical electric device. In this study, indium tin oxide (ITO ; Sn-doped $In_2O_3$) thin films were deposited on $SiO_2$/soda-lime glass plates by a dc magnetron sputtering technique. The crystallinity and electrical properties of the films were investigated by X-ray diffraction(XRD), atomic force microscopy (AFM) scanning and 4-point probe. The optical transmittance of ITO films in the range of 300-1000nm were measured with a spectrophotometer. As a result, we obtained polycrystalline structured ITO films with (222), (400), and (440) peak. Transmittance of all the films were higher than 90% in the visible range.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2333-2337
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• 2007

Nanoporous TiO2 and ZrO2 thin films were spin-coated using a surfactant-templated approach from Pluronic P123 (EO20PO70EO20) as the templating agent, titanium alkoxide (Ti(OC4H9)4) as the inorganic precursor, and butanol as a the solvent. The control of the electronic structure of TiO2 is crucial for its various applications. We found that the band gap of the hybrid nanoporous thin films can be easily tuned by adding an acetylacetonestabilized Zr(OC4H9)4 precursor to the precursor solution of Ti(OC4H9)4. Pores with a diameter of 5 nm-10 nm were randomly dispersed and partially connected to each other inside the films. TiO2 and ZrO2 thin films have an anatase structure and tetragonal structure, respectively, while the TiO2-ZrO2 hybrid film exhibited no crystallinity. The refractive index was significantly changed by varying the atomic ratio of titanium to zirconium. The band gap for the nanoporous TiO2 was estimated to 3.43 eV and that for the TiO2-ZrO2 hybrid film was 3.61 eV.