• Korean Journal of Materials Research
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• v.29 no.5
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• pp.328-335
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• 2019

Nb-doped $TiO_2$(NTO) coated NiCrAl alloy foam for hydrogen production is prepared using ultrasonic spray pyrolysis deposition(USPD) method. To optimize the size and distribution of NTO particles based on good physical and chemical stability, we synthesize particles by adjusting the weight ratio of the Nb precursor solution(5 wt%, 10 wt% and 15 wt%). The morphological, chemical bonding, and structural properties of the NTO coated NiCrAl alloy foam are investigated by X-ray diffraction(XRD), X-ray photo-electron spectroscopy(XPS), and Field-Emission Scanning Electron Microscopy(FESEM). As a result, the samples of controlled Nb weight ratio exhibit a common diffraction pattern at ${\sim}25.3^{\circ}$, corresponding to the(101) plane, and have chemical bonding(O-Nb=O) at 534 eV. The NTO particles with the optimum weight ratio of N (10 wt%) show a uniform distribution with a size of ~18.2-21.0 nm. In addition, they exhibit the highest corrosion resistance even in the electrochemical stability estimation. As a result, the introduction of NTO coated NiCrAl alloy foam by USPD improves the chemical stability of the NiCrAl alloy foam by protecting the direct electrochemical reaction between the foam and the electrolyte. Thus, the optimized NTO coating can be proposed for excellent protection of NiCrAl alloy foam for hydrocarbon-based steam methane reforming(SMR).

• Korean Journal of Materials Research
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• v.34 no.1
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• pp.55-62
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• 2024

Fluorine-doped tin oxide (FTO) has been used as a representative transparent conductive oxide (TCO) in various optoelectronic applications, including light emitting diodes, solar cells, photo-detectors, and electrochromic devices. The FTO plays an important role in providing electron transfer between active layers and external circuits while maintaining high transmittance in the devices. Herein, we report the effects of substrate rotation speed on the electrical and optical properties of FTO films during ultrasonic spray pyrolysis deposition (USPD). The substrate rotation speeds were adjusted to 2, 6, 10, and 14 rpm. As the substrate rotation speed increased from 2 to 14 rpm, the FTO films exhibited different film morphologies, including crystallite size, surface roughness, crystal texture, and film thickness. This FTO film engineering can be attributed to the variable nucleation and growth behaviors of FTO crystallites according to substrate rotation speeds during USPD. Among the FTO films with different substrate rotation speeds, the FTO film fabricated at 6 rpm showed the best optimized TCO characteristics when considering both electrical (sheet resistance of 13.73 Ω/□) and optical (average transmittance of 86.76 % at 400~700 nm) properties with a figure of merit (0.018 Ω^-1).

• Solar Energy
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• v.17 no.2
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• pp.55-66
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• 1997

The structural and optoelectronic properties of polycrystalline CdS films up to several microns in thickness, fabricated by three different methods, are compared to one another for the purpose of preparing CdTe/CdS solar cells. All films were deposited on an indium tin oxide on glass substrate. The three methods are: 1) alternated spraying of cation and anion solution at room temperature; 2) spray pyrolysis with substrate temperature up to $500^{\circ}C$; 3) chemical bath deposition (CBD). Deposited films were thermally treated in various ways. All films showed a well-developed wurtzite structure. Films grown by the alternated-spray method and the chemical bath method consist of randomly-oriented crystallites with dimensions <0.5 microns. Annealing at $400^{\circ}C$ increases the crystallite size slightly. Films which were grown by pyrolysis at substrate temperatures from $400^{\circ}C\;to\;500^{\cir\c}C$ were oriented in the <002> direction. For growth by pyrolysis at $500^{\circ}C$, the surface is rough on a lateral scale of 0.1 to 0.3 microns. The optical band gap and defect states are investigated by optical absorption, photoluminescene, Raman, and photothermal deflection spectroscopies.

• Fashion & Textile Research Journal
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• v.24 no.1
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• pp.138-145
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• 2022

Today, graphene loaded textiles are being considered promising smart clothing due to their high conductivity. In this study, we reported reduced graphene oxide(r-GO) deposited pure cotton fabrics fabricated with a colloidal solution of graphene(GO), using a one-step aerosol spray pyrolysis(ASP) process and their potential application on smart textiles. The ASP process is advantageous in that it is easily implementable and can be applied for continuous processing. Moreover, this process has never been applied to deposit r-GO on pure cotton fabric. The field emission-scanning microscopy (FE-SEM) observation, Fourier transform-infrared(FT-IR) analysis, Raman spectroscopy, X-ray diffraction(XRD) analysis, and ultraviolet transmittance(UVT) were used to evaluate material properties of the r-GO colloids. The resistance was also measured to evaluate the electrical conductivity of the specimens. The results revealed that the r-GO was successfully deposed on specimens, and the specimen with the highest electrical conductivity demonstrated an electrical resistance value of 2.27 kΩ/sq. Taken together, the results revealed that the ASP method demonstrated a high potential for effective deposition of r-GO on cotton fabric specimens and is a prospect for the development of conductive cotton-based smart clothing. Therefore, this study is also meaningful in that the ASP process can be newly applied by depositing r-GO on the pure cotton fabric.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.266.1-266.1
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• 2016

최근 태양전지에 대한 연구가 활발하기 이루어지고 있다. 그 중 본 연구에선 태양전지에 사용될 광흡수층에 대한 연구로 광흡수층은 광흡수계수와 밴드갭의 영향을 받고 SnS가 적합한 특성을 지니고 있다고 판단하여 이에 대한 합성과 특성에 대한 연구를 진행 하였다. SnxSy 박막은 Electrochemical deposition, Spray pyrolysis deposition, Furnace를 이용하는 등 다양한 방법이 있다. 이러한 방법들은 대부분 막질이 좋지 않다고 알려져 있는데 그 중 Furnace를 이용하는 방법은 간단하며 넓은 면적에 쉽게 증착이 가능하다는 장점이 있지만 S의 양과 온도에 민감하다. 본 연구에서는 Sn과 SnO 박막을 전구체로 사용하였으며 S의 양과 온도를 조절하여 로를 이용하여 합성하였다. 이에 대한 조성 및 구조적 특성을 분석하기 위해 XRD를 전기적 특성을 확인하기 위하여 Hall effect measurement를 통하여 측정하였다.

• Carbon letters
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• v.9 no.1
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• pp.17-22
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• 2008

A carbon nanotube (CNT) of diameter ~20 nm has been synthesized by spray pyrolysis of turpentine oil using Ni/Fe catalyst. Pellet of CNTs has been used as a target to produce semiconducting carbon thin film of band gap 1.4 eV. Presence of oxygen pressure in the pulse laser deposition (PLD) chamber helped to control the $sp^3/sp^2$ ratio to achieve the desired band gap. Results are discussed with the help of Raman spectra, SEM TEM micrographs and optical measurements suggest that semiconducting carbon thin film deposited by PLD technique has retained its nanotubes structure except that its diameter has increased from 20 nm to 150 nm.

• Journal of Sensor Science and Technology
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• v.5 no.3
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• pp.41-48
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• 1996

We developed SAW gas sensor for monitoring SOx gas with high sensitivity. It was fabricated as a microsensor for detecting SOx gas by depositing sensing material on SAW device. As a detecting layer material, CdS was selected. Deposition of CdS in the form of thin films was carried out by the ultrasonic spray pyrolysis method using ultrasonic spray nozzle. Thin films with the uniform and large surface area for sensors were deposited. The stable pyrolysis environment provided by uniform and fine droplets formed by spray nozzle made it possible to obtain thin films with excellent quality. The minimum grain size of the CdS thin films was about 50 nm when deposited at $300^{\circ}C$. SAW gas sensors showed reasonable sensitivity and reproducibility. Further studies are required to investigate the interference of other gases to SOx gas detection.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.675-675
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• 2013

CIGS thin films have received a great attention as a promising material for solar cells due to their high absorption coefficient, appropriate bandgap, long-term stability, and low cost production. CIGS thin films have been deposited by various methods such as co-evaporation, sputtering, spray pyrolysis and electro-deposition. In this study, Cu(In,Ga)Se2(CIGS) thin films were prepared using a single quaternary target by rf magnetron sputtering. The effect of sulfurization on the structural, compositional and electrical properties of the films was examined in order to develop the deposition process. An optimal sulfurization process will be selected for the preparation of CIGS thin films with good structural, optical and electrical properties by applying various sulfurization processes. In addition, the electrical properties of CIGS thin films were investigated by post-deposition annealing process. The carrier concentration of CIG(SSe) thin films after sulfurization was increased from $10^{14}cm^{-3}$ to $10^{16}cm^{-3}$ and the resistivity was increased from 10 ${\Omega}cm$ to $10^3$ ${\Omega}cm$. It is confirmed that CIG(SSe) thin films prepared at optimal deposition condition have similar atomic ratio to the target value after sulfurization.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.159-159
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• 2011

Among the semiconductor ternary compounds in the I-III-$VI_2$ series, $CulnS_2$ ($CulnSe_2$) are one of the promising materials for photovoltaic applications because of the suitability of their electrical and optical properties. The $CuInS_2$ thin film is one of I-III-$VI_2$ type semiconductors, which crystallizes in the chalcopyrite structure. Its direct band gap of 1.5 eV, high absorption coefficient and environmental viewpoint that $CuInS_2$ does not contain any toxic constituents make it suitable for terrestrial photovoltaic applications. A variety of techniques have been applied to deposit $CuInS_2$ thin films, such as single/double source evaporation, coevaporation, rf sputtering, chemical vapor deposition and chemical spray pyrolysis. This is the first report that $CuInS_2$ thin films have been prepared by Aerosol Jet Deposition (AJD) technique which is a novel and attractive method because thin films with high deposition rate can be grown at very low cost. In this study, $CuInS_2$ thin films have been prepared by Aerosol Jet Deposition (AJD) method which employs a nozzle expansion. The mixed fluid is expanded through the nozzle into the chamber evacuated in a lower pressure to deposit $CuInS_2$ films on Mo coated glass substrate. In this AJD system, the characteristics of $CuInS_2$ films are dependent on various deposition parameters, such as compositional ratio of precursor solution, flow rate of carrier gas, stagnation pressure, substrate temperature, nozzle shape, nozzle size and chamber pressure, etc. In this report, $CuInS_2$ thin films are deposited using the deposition parameters such as the compositional ratio of the precursor solution and the substrate temperature. The deposited $CuInS_2$ thin films will be analyzed in terms of deposition rate, crystal structure, and optical properties.

• Journal of Powder Materials
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• v.25 no.1
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• pp.54-59
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• 2018

Sb-doped $SnO_2$ (ATO) transparent conducting films are fabricated using horizontal ultrasonic spray pyrolysis deposition (HUSPD) to form uniform and compact film structures with homogeneously supplied precursor solution. To optimize the molar concentration and transparent conducting performance of the ATO films using HUSPD, we use precursor solutions of 0.15, 0.20, 0.25, and 0.30 M. As the molar concentration increases, the resultant ATO films exhibit more compact surface structures because of the larger crystallite sizes and higher ATO crystallinity because of the greater thickness from the accelerated growth of ATO. Thus, the ATO films prepared at 0.25 M have the best transparent conducting performance ($12.60{\pm}0.21{\Omega}/{\square}$ sheet resistance and 80.83% optical transmittance) and the highest figure-of-merit value ($9.44{\pm}0.17{\times}10^{-3}{\Omega}^{-1}$). The improvement in transparent conducting performance is attributed to the enhanced carrier concentration by the improved ATO crystallinity and Hall mobility with the compact surface structure and preferred (211) orientation, ascribed to the accelerated growth of ATO at the optimized molar concentration. Therefore, ATO films fabricated using HUSPD are transparent conducting film candidates for optoelectronic devices.