Growth and Properties of CrNx/TiNy/Al Based on N2 Gas Flow Rate for Solar Thermal Applications

Gun-Eik Jang,Sang-Jun Ju,Yeo-Won Jang,Hyun-Hoo Kim,Cheon Lee 한국전기전자재료학회 2016 Transactions on Electrical and Electronic Material Vol.17 No.3

The CrN/TiN/Al thin films for solar selective absorber were prepared by dc reactive magnetron sputtering with multitargets. The binary nitride CrN layer deposited with change in N2 gas flow rates. The gas mixture of Ar and N2 was animportant parameter during sputtering deposition because the metal volume fraction (MVF) was controlled by theN2 gas flow rate. In this study, the crystallinity and surface properties of the CrN/TiN/Al thin films were estimated byX-ray diffraction (XRD), atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The composition and depth profile of thin films were investigated using Auger electron spectroscopy (AES). Theabsorptance and reflectance with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a rangeof 300~1,100 nm.

Micromachined MoO₃ Gas Sensor with Low Power Consumption of 0.5 Watt

Jang, Gun-Eik,Wu Q.H.,Liu C.C. The Korean Institute of Electrical and Electronic 2005 Transactions on Electrical and Electronic Material Vol.6 No.4

A new $MoO_3$ based microsensor with low power consumption was presented. Typical size of sensor was 5mm in width and 8mm in length. As a sensitive electrode, $MoO_3$ was successfully fabricated by IC technology on pyrex glass of $250{\mu}m$ in thickness. After annealing at $550^{\circ}C$ for 3hrs, the film was fully crystallized and demonstrated as pure $MoO_3$ structure. The grain size of $MoO_3$ was plat like and typical size was about $1{\mu}m$. Based on the results of sensitivity measurement, $MoO_3$ microsensor shows especially high selectivity to $H_2$ reducing gas atmosphere. The applied heater power was lower than 0.5 Watt.

Electronic Structure, Bonding, and Lithium Migration Effects of the Mixed Conductor β - LiAl

장건익(Gun-Eik Jang),I.M. Curelaru 한국진공학회(ASCT) 1996 Applied Science and Convergence Technology Vol.5 No.3

전자구조(valence 와 conduction band) 해석을 통하여 이론상으로 현저한 금속 특성을 갖는다고 알려진 혼합 전도체 β-LiAl은 실제 이론과는 달리 Fermi level 에서 하나의 quasi-gap 이 존재하고 conduction 상태가 상당히 localized 되어 있음이 본 연구의 세부적 실험을 통하여 밝혀졌다. 또한 기계적 표면처리나 입자 bombardment(전자나 이온)을 통하여 야기되는, Li 이온의 복잡한 이동 거동에 관하여도 고찰하였다. Detailed experimental studies of the electronic structure of the valence and conduction bands of the mixed conductor β-LiAl indicate that a quasi-gap opens at the Fermi level, and the conduction states are highly localized, as opposed to the theoretical band structure calculations that predict predominant metallic behavior. Evidence for complex lithium migration effects involving the surface of LiAl, induced by particle (electron or ion) bombardment and mechanical treatment, has been obtained as a byproduct of these experiments.

화학센서용 다공성 γ-Fe2O3 박막 제조

장건익,김범진,임일성 한국센서학회 1999 센서학회지 Vol.8 No.2

γ-Fe₂O₃ thin films on Al₂O₃ substrate were prepared by the oxidation of Fe₃O₄ thin films processed by PECVD(Plasma-Enhanced Chemical Vapor Deposition) technique. The phase transformation of γ-Fe₂O₃ thin films was mainly controlled by the substrate temperature and oxidation process of Fe₃O₄ phase. Fe₃O₄ phase was obtained at the deposition temperature of 200∼300℃. Fe₃O₄ phase could be transformed into γ-Fe₂O₃ phase under controlled oxidation at 280∼300℃. Fe₃O₄ and γ-Fe₂O₃ obtained by oxidation of Fe₃O₄ phase had the same spinel structure and were coexisted. The oxidized γ-Fe₂O₃ thin film on Al₂O₃ substrate showed a porous island structure.

Refractive-index matched layers applied to flexible conductive MTO/Ag/MTO multilayer films on the PET substrate

Sangmoo Yoon,Gun-Eik Jang 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.1

A hybrid structure of Mn (2.59 wt.%) doped SnO2 (MTO)/Ag/MTO films with refractive index matching layers (IMLs) wasdeposited on PET substrate by a RF/DC magnetron sputtering method at room temperature. To match the refractive index(n) of MTO/Ag/MTO/PET film, high and low refractive index materials of MTO (n = 2.02) and SiO2 (n = 1.52) were placedbetween MTO/Ag/MTO and PET substrate, respectively. In order to evaluate the effect of IMLs on the reflectivity and colorvariation, an optical simulation program, Essential Macleod Program (EMP) was adopted, in advance. From EMP simulation,the multilayer film of MTO (40 nm)/Ag (13 nm)/MTO (40 nm) with optimized IMLs of SiO2 (120 nm)/MTO (10 nm) showsthe excellent optical transmittance above 86.1% at the 550 nm wavelength, and the pattern visible defect was reduced ascompared with the reference film of MTO/Ag/MTO/PET film without IMLs. From the bending test, the multilayer film ofMTO (40 nm)/Ag (13 nm)/MTO (40 nm)/SiO2 (90 nm)/MTO (10 nm)/PET showed excellent flexible properties. There was only10% resistance variation under 10,000 bending cycle with curvature radius of 5 mm.

Properties of $Sr_{0.8}Bi_{2.3}{(Ta_{1-x}Nb_{x})}_{2}O_{9+{\alpha}}$ Thin Films

Park, Sang-Jun,Jang, Gun-Eik The Korean Institute of Electrical and Electronic 2000 Transactions on Electrical and Electronic Material Vol.1 No.1

Polycrystalline SBTN layered ferroelectric thin film with various Nb mole ratios were prepared by sol-gel method Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperature and characterized in terms of phase and microstructure. The films were crystallized with a high (105) diffraction intensity and had rodike structure, SBTN films fired at 800$^{circ}C$ revealed standard hysteresis loops with no fatigue for up to 10$^{10}$ cycles. At an applied voltage of 5V the dielectric constant($varepsilon$) , dissipation factor (tan $delta$), remanent polarization(ZPr) and coercive field(Ec) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$) $O_{9+}$$alpha$/ thin film(x=0.1) prepared on Pt/ $SiO_2$/Si (100) were about 277.7, 0.042, 3.74$mu$C/$textrm{cm}^2$, and 24.8kv/cm respectively.ly.y. respectively.ly.y.y..

Effect of ZnO Buffer Layers on the Crystallization of ITO Thin Film at Low Temperature

Chung-Heon Seong,신용준,Gun-Eik Jang 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.4

In the present study, a ZnO thin film, as a buffer layer of ITO (indium tin oxide) film was deposited on glass substrates by RF magnetron sputtering at low temperature of 150℃. In order to estimate the optical characteristics and compare with the experimental results in Glass/ZnO(100 nm)/ITO(35 nm) multilayered film, the simulation program, EMP (Essential Macleod Program) was adopted. The sheet resistance and optical transmittance of the films were measured using the four-point probe method and spectrophotometer, respectively. From X-ray diffraction patterns, all the films deposited at 150℃ demonstrated only the amorphous phase. Optical transmittance was the highest at a ZnO thickness of 100 nm. The ITO(35 nm)/ZnO(100 nm) film exhibits an optical transmittance of >92% at 550 nm. The multilayered film showed an electrical sheet resistance of 407 Ω/sq., which is significantly better than that of a singlelayer ITO film without a ZnO buffer layer (815 Ω/sq.).

Effect of SiO₂/ITO Film on Energy Conversion Efficiency of Dye-sensitized Solar Cells

Woo, Jong-Su,Jang, Gun-Eik The Korean Institute of Electrical and Electronic 2015 Transactions on Electrical and Electronic Material Vol.16 No.6

Multilayered films of ITO (In₂O₃:SnO₂ = 9:1)/SiO₂ were deposited on soda-lime glass by RF/DC magnetron sputtering at 500℃ to improve the energy conversion efficiency of dye-sensitized solar cells (DSSCs). The light absorption of the dye was improved by decrease in light reflectance from the surface of the DSSCs by using an ITO film. In order to estimate the optical characteristics and compare them with experimental results, a simulation program named EMP (essential macleod program) was used. EMP results revealed that the multilayered thin films showed high transmittance (approximate average transmittance of 79%) by adjusting the SiO₂ layer thickness. XRD results revealed that the ITO and TiO₂ films exhibited a crystalline phase with (400) and (101) preferred orientations at 2 θ = 26.24° and 35.18°, respectively. The photocurrent-voltage (I-V) characteristics of the DSSCs were measured under AM 1.5 and 100 mW/cm² (1 sun) by using a solar simulator. The DSSC fabricated on the ITO film with a 0.1-nm-thick SiO₂ film showed a Voc of 0.697 V, J_sc of 10.596 mA/cm² , FF of 66.423, and calculated power conversion efficiency (η_AM1.5) of 5.259%, which was the maximum value observed in this study.

A Comparative Study on the Various Blocking Layers for Performance Improvement of Dye-sensitized Solar Cells

Woo, Jong-Su,Jang, Gun-Eik The Korean Institute of Electrical and Electronic 2013 Transactions on Electrical and Electronic Material Vol.14 No.6

In this study, short-circuit preventive layer (blocking layer) was deposited between conductive transparent electrode and porous $TiO_2$ film in the DSSCs. As blocking layer, we selected the metal-oxide such as $TiO_2$, $Nb_2O_5$ and ZnO. The sheet resistance with each different blocking layers were 18 ${\Omega}/sq.$ for the $TiO_2$, 10 ${\Omega}/sq.$ for the $Nb_2O_5$ and 8 ${\Omega}/sq.$ for the ZnO, while the RMS (Root Mean Square) roughness value of DSSCs were 39.61 nm for the $TiO_2$, 41.84 nm for the $Nb_2O_5$ and 36.14 nm for the ZnO respectively. From the results of photocurrent-voltage curves, a sputtered $Nb_2O_5$ blocking layer showed higher performance on 2.64% of photo-electrochemical properties. The maximum of conversion efficiency which was achieved under 1 sun irradiation by depositing the blocking layer increased up to 0.56%.

Effect of SiO₂ and Nb₂O₅ Buffer Layer on Optical Characteristics of ITO Thin Film

Kwon, Yong-Han,Jang, Gun-Eik The Korean Institute of Electrical and Electronic 2015 Transactions on Electrical and Electronic Material Vol.16 No.1

This paper presents the results of the optical characteristics of ITO thin film with different buffer layer thicknesses of $SiO_2$ and $Nb_2O_5$ for touch sensor application. $SiO_2$ and $Nb_2O_5$ buffer layers were deposited using RF magnetron sputtering equipment. The buffer layers were inserted between glass and ITO layers. In order to compare with the experimental results, the Essential Macleod Program (EMP) was adopted. Based on EMP simulation, the [$Nb_2O_5{\mid}SiO_2{\mid}ITO$] multi-layered thin film exhibited high transmittance of more than 85% in the visible region. The actual experimental results also showed transmittance of more than 85% in the visible region, indicating that the simulated results were well matched with the experimental results. The sheet resistance of ITO based film was about $340{\Omega}/sq$. The surface roughness maintained a relatively small value within the range of 0.1~0.4 nm when using the $Nb_2O_5$ and $SiO_2$ buffer layers.