• 한국태양에너지학회:학술대회논문집
• /
• 2011.04a
• /
• pp.116-120
• /
• 2011

In this paper, we studied the optimization of the screen pringting method for crystalline silicon solar cell fabrication. The 156 * 156 mm2 p-type silicon wafers with $200{\mu}m$ thickness and $0.5-3{\Omega}cm$ resistivity were used after texturing, doping, and passivation. Screen printing method is a common way to make the c-Si solar cell with low-cost and high-efficiency. We studied the optimized condition for screen printing with crystalline silicon solar cell as changing the printing direction (finger line or bus bar), finger width, and mesh angle. As a result, the screen printing with finger line direction showed higher finger height and better conversion efficiency, compared with one with bus bar direction. The experiments with various finger widths and mesh angles were also carried out. The characteristics of solar cells was obtained by measuring light current-voltage, optical microscope and electroluminescence.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.3
• /
• pp.852-856
• /
• 2011

The lithium ion diffusion coefficients of bare, carbon-coated and Cr-doped $LiFePO_4$ were obtained by fitting the discharge curves of each half cell with Li metal anode. Diffusion losses at discharge curves were acquired with experiment data and fitted to equations. Theoretically fitted equations showed good agreement with experimental results. Moreover, theoretical equations are able to predict lithium diffusion coefficient and discharge curves at various discharge rates. The obtained diffusion coefficients were similar to the true diffusion coefficient of phase transformation electrodes. Lithium ion diffusion is one of main factors that determine voltage drop in a half cell with $LiFePO_4$ cathode and Li metal anode. The high diffusion coefficient of carbon-coated and Cr-doped $LiFePO_4$ resulted in better performance at the discharge process. The performance at high discharge rate was improved much as diffusion coefficient increased.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1791-1793
• /
• 2000

본 연구에서는 다결정 실리콘 박막 트랜지스터(poly-Si TFTs)에서의 소오스 및 드레인 영역 형성을 위해 PSG (phosphosilicate glass)와 BSG (borosilicate glass) 박막을 도핑 물질(dopant)로 하여 저온에서 엑시머 레이저(eximer laser)로 활성화하는 공정을 제안한다. 이 실험을 통해 소스 가스인 $PH_3$와 $SiH_4$의 유량비, 레이저 에너지 밀도와 레이저 조사 횟수를 변화시키면서 면저항(sheet resistance)과 불순물의 확산 깊이(diffusion depth)를 성공적으로 조절하였다. 불순물의 확산 깊이와 표면 농도는 레이저 에너지 밀도와 조사 횟수를 증가시킴에 따라 증가하였으며 그 결과 최소 면저항 값은 인(P)의 경우 450$\Omega/\square$을 얻었고 붕소(B)의 경우 1100$\Omega/\square$을 얻었다. 이러한 실험결과는 제안된 방법을 통해 poly-Si TFTs 에서 소오스, 드레인 영역의 도핑 공정을 수행할 수 있음을 보여준다.

• Progress in Superconductivity and Cryogenics
• /
• v.16 no.1
• /
• pp.27-31
• /
• 2014

2G HTS tapes are widely used for various electric machines. In addition, stacked or parallel connected HTS tapes are essentially used to raise transport current level for large capacity electric machines. Therefore, critical current characteristic of stacked tapes need to be studied. Recently developed 2G HTS tapes are fabricated with various defects doping so that tapes possess pinning center to improve the critical current characteristic. During this process, the critical current is determined minimum value in not perpendicular magnetic field but a specific magnetic field angle according to the reported research. However, the effects of magnetic field angle to critical current of multi-stacked 2G HTS tapes have not been examined. In this paper, field coil which is a race-track coil wound by using an HTS tape with iron-core was fabricated to apply angle adjustable magnetic field to the 2G HTS tape samples. We measured critical current of single and multi-stacked two tapes that have different characteristic depending on various magnetic field angle and magnitude in liquid nitrogen environment. Furthermore, results of single and multi-stacked tapes were compared and analyzed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.1
• /
• pp.12-16
• /
• 2009

Current sensing in power semiconductors involves sensing of over-current in order to protect the device from harsh conditions. This technique is one of the most important functions in stabilizing power semiconductor device modules. The sense FET is very efficient method with low power consumption, fast sensing speed and accuracy. In this paper, we have analyzed the characteristics of proposed sense FET and optimized its electrical characteristics to apply conventional 450 V power MOSFET by numerical and simulation analysis. The proposed sense FET has the n-drift doping concentration $1.5{\times}10^{14}cm^{-3}$, size of $600{\um}m^2$ with $4.5\;{\Omega}$, and off-state leakage current below $50{\mu}A$. We offer the layout of the proposed sense FET to process actually. The offerd design and optimization methods are meaningful, which the methods can be applied to the power devices having various breakdown voltages for protection.

• Journal of IKEEE
• /
• v.14 no.4
• /
• pp.277-282
• /
• 2010

In this paper, we proposed ZnO trench Static Induction Transistor(SIT). Because The compound semiconductor had superior thermal characteristics, ZnO and SiC power devices is next generation power semiconductor devices. We carried out modeling of ZnO SIT with 2-D device and process simulator. As a result of modeling, we obtained 340V breakdown voltage. The channel thickness was 3um and the channel doping concentration is 1e17cm-3. And we carried out thermal characteristics, too.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.05a
• /
• pp.55.2-55.2
• /
• 2009

A polymer electrolyte membrane (PEM) fuel cell has been getting large interest as a typical issue in useful applications. The PEMFC is composed of a membrane, catalyst and the bipolar plate. SnOx:F films on SUS316 stainless steel were prepared as a function of substrate with using electron cyclotron resonance-metal organic chemical vapor deposition (ECR-MOCVD) in order to achieve the corrosion-resistant and low contact resistance bipolar plates for PEM fuel cells. The SnOx:F films coated on SUS316 substrate at surface plasma treatment for excellent stability, before/after heat treatment for good crystalline structure and microwave power for were characterized by X-ray diffraction (XRD), auger electron microscopy (AES) and field emission-scanning electron microscopy (FE-SEM). The SnOx:F film coated on SUS316 substrate with various process parameters were able to observe optimum interfacial contact resistance (ICR) and corrosion resistance. It can be concluded that fluorine-doping content plays an important function in electrical property and characteristic of corrosion-protective film.

• Korean Journal of Optics and Photonics
• /
• v.4 no.1
• /
• pp.108-113
• /
• 1993

In this paper, we study the photorefractive properties of Fe indiffused $LiNbO_3$ waveguides. Comparing the photorefractive properties of $Fe:LiNbO_3$ with those of $LiNbO_3$, we confirm the increase of the diffraction efficiency and the sensitivity by Fe doping. Also for the photorefractive properties of $Fe:LiNbO_3$ waveguides with different ambient gases, the diffaction efficiency and the sensitivity of $Fe:LiNbO_3$ indifused in pure argon gases are the highest and its decay time is the shortest. Therefore, it is recommended that pure argon gases be used in Fe indiffusion process for good optical switches with photorefractive effect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.05a
• /
• pp.152-153
• /
• 1994

A recessed $n^{+}$-p junction diode with the serf-aligned structure is proposed and fabricated by using the polysilicon as an $n^{+}$ diffusion source. The diode structure can be applicable to the emitter-base formation of high performance bipolar device and the $n^{+}$ polysilicon emitter has an important effect on the device characteristics. The considered parameters for the polysilicon formation are the deposition condition $As^{+}$ dose for the doping of the polysilicon, and the annealing using RTP system. The vertical depth profiles of the fabricated diode are obtained by SIMS. The eleotrical characteristics are analyzed in trims of the ideality factor of diode (n), contact resistance arid reverse leakage current. The $As_{+}$ dose for the formation of good junction is current. The $As^{+}$ dose for the formation of goodjunctions is about 1∼2${\times}$$10^{16}$$cm^{-2}$ at given RTA condition ($1100^{\circ}C$, 10 sec). The $n^{+}$-p structure is successfully applied to the self-aligned bipolar device adopting a single polysilicon technology.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.792-794
• /
• 2010

본 연구는 PC1D를 이용하여 태양전지 전류전압 특성곡선및 효율을 분석한 연구이다. 태양전지 전류전압 특성곡선에서 제4상한부분의 면적은 태양전지의 효율을 나타낸다. 곡선인자(Fill Factor)는 개방전압과 단락 전류의 곱에 대한 최대 출력전압과 최대 출력전류의 곱한 값의 비율이다. 본 논문은 태양전지의 최대 효율을 얻기 위해서 도핑 농도를 $1{\times}10^{14}cm^{-3}$부터 $1{\times}10^{17}cm^{-3}$까지 변화시키면서 태양전지의 전류전압 특성곡선 및 최대효율을 분석하였다.