• Current Photovoltaic Research
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• v.10 no.1
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• pp.23-27
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• 2022

In this study, we investigate organic-inorganic halide perovskite solar cells with a vacuum thermal evaporated hole transporting layer (NPB/MoO_3-x). By replacing solution process based Spiro-MeOTAD with vacuum thermal evaporation based NPB/MoO_3-x, a thin hole transporting layer was implemented. In addition, parasitic absorption that may occur during the doping process was eliminated by excluding solution process doping. In a solar cell with a thin vacuum thermal evaporated hole transporting layer, the short-circuit current density (Jsc) increased to 23.93 mA/cm², resulting in the highest power converstion efficiency (PCE) at 18.76%. Considering these results, it is essential to control the thickness of hole transporting layer located at the top in solar cell configuration.

• Current Photovoltaic Research
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• v.1 no.1
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• pp.59-62
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• 2013

We investigated the effects of ZnO thin film deposition methods on the performance of inverted polymer solar cells with a structure of ITO/ZnO/P3HT:PCBM/MoO3/Al. The ZnO thin films were deposited by various methods (spin coating of nanoparticles, sol-gel process, atomic layer deposition) and their morphology was analyzed by atomic force microscopy (AFM). The device with ZnO nanoparticle thin films showed the highest power conversion efficiency of 3 % with low series resistance and high shunt resistance. The superior performance of the device with the ZnO nanoparticle layer is attributed to better electron extraction capability.

• Journal of the Korean Ceramic Society
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• v.42 no.9 s.280
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• pp.624-630
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• 2005

To investigate the possibility of the $ZrO_2$ buffer layer as the insulator for the Metal-Ferroelectric-Insulator-semiconductor (MFIS) structure, $ZrO_2$ and $SrBi_2Ta_2O_9$ (SBT) thin films were deposited on the P-type Si(111) wafer by the R.F. magnetron-sputtering method. According to the process with and without the post-annealing of the $ZrO_2$ buffer layer and SBT thin film, the diffusion amount of Sr, Bi, Ta elements show slight difference through the Glow Discharge Spectrometer (GDS) analysis. From X-ray Photoelectron Spectroscopy (XPS) results, we could confirm that the post-annealing process affects the chemical binding condition of the interface between the $ZrO_2$ thin film and the Si substrate. Compared to the MFIS structure without the post-annealing of the $ZrO_2$ buffer layer, memory window value of MFlS structure with post-annealing of the $ZrO_2$ buffer layer were considerably improved. The window memory of the Pt/SBT (260 nm, $800^{\circ}C)/ZrO_2$ (20 nm) structure increases from 0.75 to 2.2 V under the applied voltage of 9 V after post-annealing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.228-233
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• 2010

We studied the optical characteristics correlated with low dielectric constants of low-k SiOCH thin films through ellipsometry. The low-k SiOCH thin films were prepared by CCP-PECVD method using BTMSM(Bis-trimethylsilylmethane) precursors deposited on p-Si wafer. The Si-O-CHx, Si-O-Si, Si-CHx, CHx and Si-H bonding groups were specified by FTIR spectroscopic spectra, and the groups coupled with the nano-porous structural organic/inorganic hybrid-type of SiOCH thin films which has extremely low dielectric constant close to 2.0. The structural groups includes highly dense pore as well as ions in SiOCH thin films affecting to complex refraction characteristics of single layer on the p-Si wafer. The structural complexity originate the complex refractive constants of the films, and resulted the elliptical polarization of the incident linearly polarized light source of Xe-light source in the range from 190 nm to 2100 nm. Phase difference and amplitude ratio between s wave and p wave propagating through SiOCH thin film was studied. After annealing, the amplitude of p wave was reduced more than s wave, and phase difference between p and s wave was also reduced.

• Journal of Sensor Science and Technology
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• v.9 no.6
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• pp.430-439
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• 2000

$In_2O_3$-based thin film sensor with 500-600 nm thick was fabricated for the detection of CO gas by rf magnetron sputtering. In order to improve both sensitivity to CO gas and selectivity to hydrogen gas containing -CH, ultra-thin transition metal Co catalyst was sputtered over $In_2O_3$ thin film and annealed at $500^{\circ}C$. Sensitivity to CO was maximum at the thickness of Co 2.1 nm and $300^{\circ}C$, and that to $C_3H_8$ was at the thickness of Co 1.4 nm and $350-400^{\circ}C$. From the x-ray photoelectron spectroscopy (XPS) result, ultra-thin Co was existed into CoO covered with $Co_2O_3$ on $In_2O_3$ particles, and thus p-n junction of $In_2O_3(n-type)$-CoO(p-type) was thought to be formed. In this p-n junction type sensors, sensing mechanism with reducing gases can be explained by the variation of depletion layer thickness formed in the interface.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.256-258
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• 2009

현재 상용화되어 있는 결정질 태양전지의 경우 높은 실리콘 가격으로 인해 저가격화에 어려움을 격고 있다. 따라서 태양전지 저가화의 한 방법으로 박막태양전지가 주목을 받고 있다. P-I-N 구조의 박막태양전지에서 각 층의 thickness, activation energy, energy bandgap은 고효율 달성을 위한 중요한 요소이다. 본 논문에서는 박막태양전지 p-layer의 가변을 통하여 고효율을 달성하기 위한 simulation을 수행하였다. 가변 조건으로는 thickness $5\sim25nm$, activation energy $0.3\sim0.6$ eV 그리고 energy bandgap $1.6\sim1.8$ eV까지 단계별로 변화시켰다. 최종 simulation 결과 p-layer의 thickness 5nm, activation energy 0.3 eV 그리고 energy bandgap 1.8 eV에서 최고 효율 11.08%를 달성하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.3
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• pp.270-272
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• 2005

The behavior of surface oxidation on cobalt silicide layer was investigated under rapid thermal oxidation (RTO) conditions. The cobalt silicide layer was prepared on p-type silicon substrates. We used Ti thin film as a capping layer in order to measure the degree of oxidation of the layer. Oxide grew faster on the cobalt silicide prepared with the Ti capping layer to reach ca $500{\AA}$ at $700^{\circ}C$ in thickness. The oxide film kept growing under $550^{\circ}C\~700^{\circ}C$ of the RTO condition, resulting in a saturated state above $500{\AA}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.436-436
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• 2009

현재 상용화되어 있는 결정질 태양전지의 경우 높은 실리콘 가격으로 인해 저가화에 어려움을 격고 있다. 따라서 태양전지 저가화의 한 방법으로 박막태양전지가 주목을 받고 있다. P-I-N 구조의 박막태양전지에서 각 층의 thickness, activation energy, energy bandgap은 고효율 달성을 위한 중요한 요소이다. 본 논문에서는 박막태양전지 P-I-N layer의 가변을 통하여 고효율을 달성하기 위한 simulation을 수행하였다. 가변 조건으로는 p-layer의 thickness, activation energy 그리고 energy bandgap을 단계별로 변화시켰고 i-layer는 thickness를 n-layer는 thickness와 activation energy를 가변하여 최적의 조건을 찾아 분석하였다. 최종 simulation 결과 p-layer의 thickness 5nm, activation energy 0.3eV 그리고 energy bandgap 1.8eV에서, i-layer thickness 400nm, n-layer thickness 30nm, activation energy 0.2eV에서 최고 효율 11.08%를 달성하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.437-437
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• 2009

현재 상용화되어 있는 결정질 태양전지의 경우 높은 실리콘 가격으로 인해 저가화에 어려움을 격고 있다. 따라서 태양전지 저가화의 한 방법으로 박막태양전지가 주목을 받고 있다. P-I-N 구조의 박막태양전지에서 I-layer 각 층의 thickness, activation energy, energy bandgap은 고효율 달성을 위한 중요한 요소이다. 본 논문에서는 박막태양전지 P-I-N layer의 가변을 통하여 고효율을 달성하기 위한 simulation을 수행하였다. 가변 조건으로는 p-layer의 thickness, activation energy 그리고 energy bandgap을 단계별로 변화시켰고 i-layer는 thickness를 n-layer는 thickness와 activation energy를 가변하여 최적의 조건을 찾아 분석하였다. 최종 simulation 결과 p-layer의 thickness 5nm, activation energy 0.3eV 그리고 energy bandgap 1.8eV에서, i-layer thickness 400nm, n-layer thickness 30nm, activation energy 0.2eV에서 최고 효율 11.08%를 달성하였다.

• Journal of Magnetics
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• v.7 no.3
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• pp.115-125
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• 2002

We proposed a novel method to evaluate the magnetic properties of the initial layer and the columnar structure separately for CoCr-based perpendicular recording media. We show that the thickness of the initial layer and the intrinsic magnetocrystalline anisotropy of columnar structure can be quantitatively evaluated using the plotted product of perpendicular anisotropy to magnetic film thickness versus magnetic film thickness ($K_{u{\bot}}^{ex{p.}}$ $\times$ d$_{mag.}$ vs. d$_{mag.}$ plot). Based on the analyses, it is found that: (1) compared with CoCrPtTa media, CoCrPtB media have relatively thin initial layer, and have fine grains with homogeneous columnar structure with c-plane crystallographic orientation; (2) CoCrPtB media can be grown epitaxially on Ru or CoCr/C intermediate layer, and as the result, the magnetic properties of the media within thin thickness region of d$_{mag.}$ $\leq$ 20 nm is significantly improved; (3) the key issue of material investigation for CoCr-based perpendicular recording media will be focused on how to fabricate c-plane-oriented columnar grains well isolated with nonmagnetic substance in epitaxial-growth media, while maintaining the thermal stability of the media.