• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제54권4호
• /
• pp.139-143
• /
• 2005

For application of carbon nano-tube (CNT) as a counter electrode materials of dye-sensitized solar cell (DSSC), the electrochemical behavior of CNT electrode was studied, employing cyclic-voltammetry (C-V) and impedance spectroscopy. Fabrication of CNT-paste and formation of CNT-counter electrode for characteristic measurement have been carried out using ball-milling and doctor blade process, respectively. Unit cell for measurements was assembled using Pt electrode, CNT electrode, and iodine-embedded electrolyte. Field emission-scanning electron microscopy (FE-SEM) was used for structural investigation of CNT powder and electrode. Sheet resistance of electrode was measured with 4-point probe method. Electrochemical properties of electrode, C-V and impedance spectrum, were studied, employing potentiogalvanostat (EG&G 273A) and lock in amplifier (EG&G 5210). As a results, the sheet resistance of CNT electrode is almost similar to that of F-doped SnO2 (FTO) coated glass substrate as approximately 10 ohm/sq. From C-V and impedance spectroscopy measurements, it was found that CNT electrode has high reaction rate and low interface reaction resistance between CNT surface and electrolyte. These results provides that CNT electrode were superior to that of conventional Pt electrode. Particularly, the reaction rate in the CNT electrode is about thrice high than Pt electrode. Therefore. CNT electrode is to be good candidate material for counter electrode in DSSC.

• 한국전기전자재료학회논문지
• /
• 제23권4호
• /
• pp.261-266
• /
• 2010

In this paper, we report the changes of electrical, structural and optical characteristics in $Ge_2Sb_2Te_5$ thin films according to an increase of Si content. The Si-doped $Ge_2Sb_2Te_5$ thin films were prepared by rf-magnetron co-sputtering method. Isothermal annealing was carried out at $N_2$ atmosphere. The crystallization speed (v) of amorphous thin films was evaluated by detecting the reflection response signals using a nano-pulse scanner (wavelength = 658 nm) with illumination power of 1~17 mW and pulse duration of 10~460 ns. Structural phase changes were evaluated by XRD, and the optical transmittance was measured in the wavelength range of 300~3000 nm using UV-vis-NIR spectrophotometer. The sheet resistance (RS) of the thin films was measured using 4 point probe. Conclusivlely, the v-value decreased with an increase of Si content, while the RS-values of both crystalline and amorphous phases were increased. In particular, fcc-to-hexagonal transition was suppressed by the added Si atoms.

• 한국전기전자재료학회논문지
• /
• 제19권11호
• /
• pp.1000-1004
• /
• 2006

In this paper, thermal stability of Ni-silicide formed on the SOI substrate with $B_{11}$ has been characterized. The sheet resistance of Ni-silicide on un-doped SOI and $B_{11}$ implanted bulk substrate was increased after the post-silicidation annealing at $700^{\circ}C$ for 30 min. However, in case of $B_{11}$ implanted SOI substrate, the sheet resistance showed stable characteristics after the post-silicidation annealing up to $700^{\circ}C$ for 30 min. The main reason of the excellent property of $B_{11}$ sample is believed to be the retardation of Ni diffusion by the boron and bottom oxide layer of SOI. Therefore, retardation of Ni diffusion is highly desirable lot high performance Ni silicide technology.

• 대한전자공학회논문지SD
• /
• 제40권11호
• /
• pp.1-8
• /
• 2003

본 논문에서는 소스/드레인 및 게이트의 불순물에 따른 실리사이드의 의존성을 면저항과 단면 특성 등의 분석을 통하여 연구하였다. 급속 열처리 후에는 As, P, BF₂, B/sub 11/ 등과 같은 불순물에 대한 먼저항의 차이가 거의 나지 않았다. 하지만 실리사이드 형성 후히 고온 열처리시에 그 특성이 매우 크게 변화하였다. BF₂를 주입한 시편에서의 특성이 가장 좋게 나타난 반면, As를 주입한 실리사이드의 특성이 가장 열화되었다. BF₂를 주입한 시편에서의 실리사이드 특성 향상은 flourine에 의한 니켈의 확산 방지 때문인 것으로 여겨진다. 그러므로 실리사이드의 성능 향상을 위해 Ni의 확산을 방지시키는 것이 매우 필요하다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.10-11
• /
• 2006

In this study, the Ni/Co/TiN (6/2/25 nm) structure was deposited for thermal stability estimation. Vacuum (30 mTorrs) annealing was carried out to compare with furnace annealing in nitrogen ambient. The proposed Ni/Co/TiN structure exhibited low temperature silicidation and wide range of rapid thermal process (RTP) windows. The sheet resistance was too high to measure after furnace annealing at $600^{\circ}C$ due to the thin thickness (15 nm) of the nickel silicide. However, the sheet resistance maintained stable characteristics up to $600^{\circ}C$ for 30 min after vacuum annealing. Therefore, the low resistance of thin film nickel silicide was obtained by vacuum annealing at $600^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.24-25
• /
• 2006

In this study, Ni silicide on the SOI substrate doped B11 is proposed to improve thermal stability. The sheet resistance of Ni-silicide utilizing pure SOI substrate increased after the post-silicidation annealing at $600^{\circ}C$ for 30 min. However, using the proposed B11 implanted substrate, the sheet resistance showed stable characteristics after the post-silicidation annealing up to $700^{\circ}C$ for 30 min.

• 대한금속재료학회지
• /
• 제48권7호
• /
• pp.660-666
• /
• 2010

30 nm thick Ni layers were deposited on a glass substrate by e-beam evaporation. Subsequently, 30 nm or 60 nm ${\alpha}-Si:H$ layers were grown at low temperatures ($<220^{\circ}C$) on the 30 nm Ni/Glass substrate by catalytic CVD (chemical vapor deposition). The sheet resistance, phase, microstructure, depth profile and surface roughness of the $\alpha-Si:H$ layers were examined using a four-point probe, HRXRD (high resolution Xray diffraction), Raman Spectroscopy, FE-SEM (field emission-scanning electron microscopy), TEM (transmission electron microscope) and AES depth profiler. The Ni layers reacted with Si to form NiSi layers with a low sheet resistance of $10{\Omega}/{\Box}$. The crystallinty of the $\alpha-Si:H$ layers on NiSi was up to 60% according to Raman spectroscopy. These results show that both nano-scale NiSi layers and crystalline Si layers can be formed simultaneously on a Ni deposited glass substrate using the proposed low temperature catalytic CVD process.

• 한국기계가공학회지
• /
• 제18권11호
• /
• pp.41-46
• /
• 2019

The purpose of this study is to examine and propose a high quality blade manufacturing method by applying ELID grinding technology to machining the tungsten carbide blade edge for MLCC sheet cutting. In this study, experiments are performed according to the abrasive type of grinding wheel, grinding method and grinding direction using the non-stop continuous dressing ELID grinding technology. By comparing and analyzing the chipping phenomena and surface roughness of both the blade grinding surface and the processed surface, a method for machining the tungsten carbide blade for cutting MLCC sheet is proposed. From the analysis of the surface roughness and chipping phenomena, it is confirmed that the use of diamond abrasive is advantageous for the blade machining. In addition, it succeeds in the machining of $6{\mu}m$ fine blade without any chipping, by using the grinding wheel #4000 with the diamond abrasive.

• Current Optics and Photonics
• /
• 제1권1호
• /
• pp.7-11
• /
• 2017

In this study, multilayered graphene was easily transferred to the target substrate in one step using thermal release tape. The transmittance of the transferred graphene according to the number of layers was measured using a spectrophotometer. The sheet resistance was measured using a four-point probe system. Graphene formed using this transfer method showed almost the same electrical and optical properties as that formed using the conventional poly (methyl methacrylate) transfer method. This method is suitable for the mass production of graphene because of the short process time and easy large-area transfer. In addition, multilayered graphene can be transferred on various substrates without wetting problem using the one-step dry transfer method. In this work, this easy transfer method was used for dielectric substrates such as glass, paper and polyethylene terephthalate, and a sheet resistance of ~240 ohm/sq was obtained with three-layer graphene. By fabricating organic solar cells, we verified the feasibility of using this method for optoelectronic devices.

• 한국재료학회지
• /
• 제29권5호
• /
• pp.317-321
• /
• 2019

We investigated the characteristics of nano crystalline silicon(nc-Si) thin-film solar cells on graphite substrates. Amorphous silicon(a-Si) thin-film solar cells on graphite plates show low conversion efficiency due to high surface roughness, and many recombination by dangling bonds. In previous studies, we deposited barrier films by plasma enhanced chemical vapor deposition(PECVD) on graphite plate to reduce surface roughness and achieved ~7.8 % cell efficiency. In this study, we fabricated nc-Si thin film solar cell on graphite in order to increase the efficiency of solar cells. We achieved 8.45 % efficiency on graphite plate and applied this to nc-Si on graphite sheet for flexible solar cell applications. The characterization of the cell is performed with external quantum efficiency(EQE) and current density-voltage measurements(J-V). As a result, we obtain ~8.42 % cell efficiency in a flexible solar cell fabricated on a graphite sheet, which performance is similar to that of cells fabricated on graphite plates.