• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1275-1276
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• 2006

As developing the information society, Lighting Emitted diode(LED) which is light source for illumination of next generation is attracted public attention. LED have many problem as narrow light view angle, high price, drift phenomenon of color coordinate, high heating problem for lower power, lower weight and small size. So, many researches have continued in a illumination as LED module type. in this problem, heating problem is very important and difficult and that is caused in decreasing phenomenon of brightness and drift phenomenon of color coordinate. so the problem of heating is urgent question for illumination of LED. In this paper, structural design of PCB changed as two type for solving the heating problem. also the properties of heating is analysed and optical properties is measured with heating image camera and spectrometer according to change in this design.

• Journal of Surface Science and Engineering
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• v.41 no.1
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• pp.28-32
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• 2008

In this paper CdS thin films, which were widely used window layer of the CdS/CdTe and the CdS/$CuInSe_2$ heterojunction solar cell, were grown by chemical bath deposition, which is a very attractive method for low-cost and large-area solar cells, and the structural, optical and electrical properties of the films was studied. As the thiourea/$CdAc_2$ mole ratio was increased, the deposition rate of CdS films prepared by CBD was increased due to increasing reaction velocity in solution and the optical bandgap was increased at higher thiourea/$CdAc_2$ mole ratio due to larger grain size and continuous microstructure. The minimum resistivity of the films was at thiourea/$CdAc_2$ mole ratio of 3.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.756-759
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• 2009

We described the growth of undoped ZnO thin films and their optical properties changing with a various growth temperature. The undoped ZnO thin films were grown on $c-Al_2O_3$ substrates using pulsed laser deposition (PLD) at room temperature, 200, 400, and $600^{\circ}C$, respectively. Field emission microscopy (FE-SEM) measurements showed that the grain size of undoped ZnO thin films are increasing as a increase of growth temperature. In addition, we were investigated that the structural and optical properties of undoped ZnO thin films by x-ray diffraction (XRD) and photoluminescence (PL) studied. Also, we could confirmed that the exciton luminescence was strongly related to charge trap by grain boundary of the samples using micro-PL measurement.

• Korean Journal of Materials Research
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• v.16 no.6
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• pp.346-350
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• 2006

Al-doped ZnO (AZO) thin films were grown on type of glass#1737 substrates by DC magnetron sputtering. The structural, electrical and optical properties of the films were investigated as a function of various plasma discharge power. The obtained films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The lowest resistivity was $6.0{\times}10^{-4}{\Omega}cm$ with the carrier concentration of $2.69{\times}10^{20}cm^{-3}$ and Hall mobility of 20.43 $cm^2/Vs$. The average transmittance in the visible range was above 90%.

• Korean Journal of Materials Research
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• v.24 no.3
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• pp.145-151
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• 2014

Solution-based Sb-doped $SnO_2$ (ATO) transparent conductive oxides using a low-temperature process were fabricated by an electrospray technique followed by spin coating. We demonstrated their structural, chemical, morphological, electrical, and optical properties by means of X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, Hall effect measurement system, and UV-Vis spectrophotometry. In order to investigate optimum electrical and optical properties at low-temperature annealing, we systemically coated two layer, four layer, and six layers of ATO sol-solution using spin-coating on the electrosprayed ATO thin films. The resistivity and optical transmittance of the ATO thin films decreased as the thickness of ATO sol-layer increased. Then, the ATO thin films with two sol-layers exhibited superb figure of merit compared to the other samples. The performance improvement in a low temperature process ($300^{\circ}C$) can be explained by the effect of enhanced carrier concentration due to the improved densification of the ATO thin films causing the optimum sol-layer coating. Therefore, the solution-based ATO thin films prepared at $300^{\circ}C$C exhibited the superb electrical (${\sim}7.25{\times}10^{-3}{\Omega}{\cdot}cm$) and optical transmittance (~83.1 %) performances.

• Journal of Surface Science and Engineering
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• v.38 no.5
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• pp.179-182
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• 2005

Indium Tin Oxide (ITO) thin films were deposited from various target densities ($98.7\%\~99.6\%$) using RF magnetron sputtering. Effect of the sputtering target densities on the structural, electrical and optical properties of deposited ITO thin films was investigated. The preferable (400) crystalline orientation peak was observed on the films deposited from > $99.0\%$ target density. Higher target density produced films with higher roughness but lower resistivity. All of the deposited films showed optical transmittance more than $85\%$ in the visible wavelength region. It is necessary to use the highest target density for sputtering deposition of ITO thin films.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.242-244
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• 2015

ZnO:Ga thin films were deposited by RF magnetron sputtering technique from ZnO (3 wt.% $Ga_2O_3$) target onto glass substrates under various RF power. The influence of RF power on the structural, electrical, and optical properties of ZnO:Ga thin films was investigated by X-ray diffraction, atomic force microscopy, Hall method and optical transmission spectroscopy. As the RF power increases from 50 to 110W, the crystallinity is deteriorated, the root main square surface roughness is decreased and the sheet resistance is increased. The increase of sheet resistance is caused by decreasing carrier concentration due to interstitial Ga ion. All films are transparent up to 80% in the visible wavelength range and the adsorption edge is a red-shift with increasing RF power.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.261-262
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• 2007

In this study we present the effect of annealing temperatures on the structural, electrical and optical characteristics of Ga-doped ZnO(GZO) films. GZO target have been deposited on corning 7059 glass substrates by DC sputtering. GZO films were annealed at temperatures of 400, 500, $600^{\circ}C$ in air ambient for 20 min. Experimental resulted in as-grown film shows the resistivity of $6{\times}10^{-1}\;{\Omega}{\cdot}cm$ and transmittance under 85%, whereas the electrical and optical properties of film annealed at $500^{\circ}C$ are enhanced up to $1.9{\times}10^{-3}\;{\Omega}{\cdot}cm$ and 90%, respectively.

• Transactions on Electrical and Electronic Materials
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• v.2 no.1
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• pp.22-26
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• 2001

ITO (Indium-tin-oxide) thin films were deposited on glass substrates by a dc magnetron sputtering system using ITO powder target. The methods of heat treatment are important factor to obtain high quality ITO films with low electrical resistivity and good optical transmittance. Therefore, both methods of the substrate temperature and post-deposition annealing temperature have been compared on the film structural, electrical and optical properties. A preferred orientations shifts from (411) to (222) peak at annealing temperature of 200$\^{C}$. Minimum resistivity of ITO film is approximately 8.7$\times$10$\^$-4/ Ωcm at substrate temperature of 450$\^{C}$. Optical transmittances at post annealing temperature above 200$\^{C}$ are 90%. As a result, the minimum value of annealing temperature that is required for the recrystallization of as-deposited ITo thin films is 200$\^{C}$.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.87.2-87.2
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• 2016

As an era of nano science approaches, the understanding on the shape and optical properties of various materials in a nanoscale range is getting important more seriously than ever. Accordingly the development of high spatial-temporal-spectral resolution measurement tools for characterization of nanomaterials/structures is highly required. Generally, the various properties of sample can be measured independently, e.g. to observe the structural property of sample, we use the scanning electron microscopy or atomic force microscopy, and to observe optical property, we have to use another independent measurement tool such as photoluminescence spectroscopy or Raman spectroscopy. In the case of nano-materials, however, it is very difficult to find out the same position of sample at every different measurement processes, and the condition of sample can be changed by the influence of first measurement. The tip enhanced Raman scattering(TERS), which can simultaneously measure the two or more information of sample with nanoscale spatial resolution, is one of solutions of this problem. In this talk, I will present our recent nano Raman scattering data of graphene that measured by TERS and optimized tip fabrication method for efficient experiment.