• Current Photovoltaic Research
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• 제6권1호
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• pp.27-30
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• 2018

The dependency of the electrical characteristics of silicon solar-cells on the depth of damaged layer induced by wire-sawing process was investigated. To compare cell efficiency with residual sawing damage, silicon solar-cells were fabricated by using as-sawn wafers having different depth of saw damage without any damaged etching process. The damaged layer induced by wire-sawing process in silicon bulk intensely influenced the value of fill factor on solar cells, degrading fill factor to 57.20%. In addition, the photovoltaic characteristics of solar cells applying texturing process shows that although the initial depth of saw-damage induced by wire-sawing process was different, the value of short-circuit current, fill-factor, and power-conversion-efficiency have an almost same, showing ~17.4% of cell efficiency. It indicated that the degradation of solar-cell efficiency induced by wire-sawing process could be prevented by eliminating all damaged layer through sufficient pyramid-surface texturing process.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권10호
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• pp.447-450
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• 2003

This paper presents a process optimization of antireflection (AR) coating on crystalline Si solar cells. Theoretical and experimental investigations were performed on a double-layer AR (DLAR) coating of MgF$_2$/CeO$_2$. We investigated CeO$_2$ films as an AR layer because they have a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. RF sputter grown CeO$_2$ film showed strong dependence on a deposition temperature. The CeO$_2$ deposited at 40$0^{\circ}C$ exhibited a strong (111) preferred orientation and the lowest surface roughness of 6.87 $\AA$. Refractive index of MgF$_2$ film was measured as 1.386 for the most of growth temperature. An optimized DLAR coating showed a reflectance as low as 2.04% in the wavelengths ranged from 0.4${\mu}{\textrm}{m}$ to 1.1${\mu}{\textrm}{m}$. We achieved the efficiencies of solar cells greater than 15% with 3.12% improvement with DLAR coatings. Further details on MgF$_2$, CeO$_2$ films, and cell fabrication parameters are presented in this paper.

• 소성∙가공
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• 제13권3호
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• pp.285-289
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• 2004

Micro tensile test specimens of thin film single crystal silicon for the most useful structural materials in MEMS (Micro Electro Mechanical System) devices were fabricated using SOI (Silicon-on-Insulator) wafers and MEMS processes. Dimensions of micro tensile test specimens were thickness of $7\mu\textrm{m}$, width of 50~$350\mu\textrm{m}$, and length of 2mm. Top and bottom silicon were etched using by deep RIE (Reactive Ion Etching). Thin film aluminum markers on testing region of specimens with width of $5\mu\textrm{m}$, lengths of 30~$180\mu\textrm{m}$ and thickness of 200 nm for measuring tensile strain were fabricated by aluminum wet etching method. Fabricated side wall angles of aluminum marker were about $45^{\circ}~50^{\circ}$. He-Ne laser with wavelength of 633nm was used for checking fringed patterns.

• Korean Chemical Engineering Research
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• 제49권4호
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• pp.432-437
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• 2011

최근 산업에서는 Czochralski(Cz) 공정에서 ingot의 생산성을 높이고 동시에 에너지 소비를 적절하게 할 수 있는 최적 설계가 요구되고 있다. 본 연구에서는 컴퓨터 시뮬레이션을 이용하여 현장에서 적용 가능한 설계 인자인 도가니(crucible) 크기, shield 모양, heater의 위치를 변동하면서 가장 최적의 생산성 및 전력 절감 설계를 찾아내는 연구를 수행하였다. 대상 공정은 직경 8 인치 태양전지용 ingot 생산 공정으로 생산성 증대를 위해 도가니 크기를 22인치에서 24인치로 바꾸어 안정적 생산이 가능한 최적설계를 찾았다. 이때 산업에서 외형변화가 허용되지 않아 단열두께만 줄여 최적설계를 찾았다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.593-596
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• 1999

This paper presents a process optimization of antireflectiun (AR) coating on crystalline Si solar cells. Theoretical and experimental investigations were performed on a doble-layer AR(DLAR) coating of MgF$_2$/CeO$_2$, We investigated CeO$_2$ films as an All layer because they hale a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. RF sputter grown CeO$_2$ film showed strong dependence on a deposition temperature. The CeO$_2$ film deposited at 400 $^{\circ}C$ exhibited a strong (111) preferred orientation and the lowest surface roughness of 6.87 $\AA$. Refractive index of MgF$_2$ film was measured as 1.386 for the most of growth temperature. An optimized DLAR coating showed a reflectance as low as 2.04 % in the wavelengths ranged from 0.4 7m to 1.1 7m. We achieved the efficiencies of solar cells greater than 15% with 3.12 % improvement with DLAR coatings . Further details on MgF$_2$, CeO$_2$ films, and cell fabrication Parameters are presented in this paper.

• 한국기계가공학회지
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• 제12권2호
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• pp.75-80
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• 2013

Cathode is an essential component used in plasma etching process which is to make micro pattern on the silicon wafer. The currently used cathodes produce particles at the high temperature plasma etching process. To overcome this problem, a 'Silicon Only Cathode' was developed. This 'Silicon Only Cathode' requires manufacturing process changes due to the change of shapes, material features, and machining characteristics of work materials. This research investigates the small hole drilling process. The conclusion is that PCD drills with twist angles of $20^{\circ}$ and $25^{\circ}$ were tested for small hole drilling and the experimental results indicate that the drill with $25^{\circ}$ twist angle drill causes less thrust force.

• 한국결정성장학회지
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• 제10권6호
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• pp.381-388
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• 2000

Czochralski 결정 성장 시스템에서 baroclinic 불안정성에 의해 발생하는 유동과 온도 변동에 대해 실험적으로 고찰하였다. 실리콘과 유사한 프란틀 수를 갖는 Wood's metal을 작동유체로 사용하고, 일체형 자석 프로브를 제작하여 멜트의 회전 유속을 측정하였다. 측정 결과 회전 유속은 멜트 바닥에 비해 자유 표면에서 빠르고 특히 결정 근처에서 유속이 증가하는 것을 확인하였다. 또한 도가니 회전 속도를 증가시키면서 속도와 온도 변동을 관찰한 결과 Ro<1.01, Ta>$9.63{\times}10^8$인 영역에서 baroclinic 불안정성이 나타나고, 이 영역에서 유동과 온도가 동일한 주파수를 가지고 변동하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1635-1636
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• 2006

In this paper, a non-vacuum packaged single crystalline silicon MEMS gyroscope is designed, fabricated and tested. To reduce air damping of the gyroscope structure for non-vacuum packaging, air damping model is used and damping is minimized by analysis. The inner and outer spring length is optimized by ANSYS simulation for rigid body motion. The gyroscope is fabricated by SiOG(Silicon On Glass) process. The performance of the gyroscope is measured to evaluate the characteristic of the gyroscope. The sensitivity, non-linearity, noise density and the bias stability are measured to 9.7693 mV/deg/s, 04265 %, 2.3 mdeg/s/rtHz and 16.1014 deg/s, respectively.

• 대한금속재료학회지
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• 제50권2호
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• pp.146-151
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• 2012

The present article shows how the fracture strength of single crystal silicon chips, which are generally used as semiconductor devices, is influenced by loading rate variation during a 3-point bending test. It was found that the fracture strength of the silicon chips slightly increases up to 4% with increasing loading rate for loading rates lower than 20 mm/min. Meanwhile, the fracture strength of the chips hardly increases with increase of loading rate to levels higher than 40 mm/min. However, there was an abrupt transition in the fracture strength within a loading rate range of 20 mm/min to 40 mm/min. This work explains through microscopic examination of the fracture surface of all test chips that such a big transition is related to the deflection of crack propagation direction from the (011) [${\bar{1}}00$] system to the (111) [${\bar{2}}11$] system in a particular loading rate (i.e. from 20 mm/min to 40 mm/min).

• 대한전자공학회논문지
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• 제24권1호
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• pp.91-96
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• 1987

Plasma etching can obtain less damaged etch surface than reactive ion etching. This study was performed to get anisotropic etching characteristics of Si using two step etching technique with C2CIF5 and SF6 gas mixture. The results show that the etch rate and aspect ratio of silicon was increased with increment of SF6 contents. The bulging phenomenon on trench side wall in the plasma one-step etching technique was eliminated by the two step etching technique. The anisotropy was decreased from 12(at 120m Torr) to 2.2(at 400m Torr) with increasing the chamber pressure. At the low rf power (350 watts) anisotrpy of silicon was obtained 7 lower than that of high rf power (650 watts. A:~9). In Summary we obtained anisotropic etching profiles of silicon with e 6\ulcornerm depth by using the plasma two-step etching technique.