• 한국결정성장학회지
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• 제20권1호
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• pp.7-11
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• 2010

단결정 실리콘 태양전지의 광학적 손실을 감소시키는 표면 텍스쳐링은 최종 셀의 효율을 향상시키기 위하여 매우 중요하다. 본 연구에서는 2-step texturing의 공정으로 기존의 텍스쳐링에서 이루어진 피라미드에 수 많은 sub-micrometer 사이즈의 구조를 형성시켰다. $AgNO_3$ 용액으로 웨이퍼 표면에 Ag코팅을 한 후, 그 웨이퍼를 다시 HF/$H_2O_2$ 용액으로 수십초 동안 식각을 거치게 된다. 결과적으로, 피라미드 위에 생성된 수 nm사이즈의 구조물들은 $AgNO_3$의 농도 및 식각 시간의 변화에 의해 그 크기와 굵기가 변화하는 것을 알 수 있었다. 웨이퍼의 표면이 2-step texturing에 의해 식각이 이루어지면 연잎의 거친 표면과 비슷해지고, 그 결과 평균 10% 이상의 반사율을 보이던 기존 웨이퍼에서 3% 이하의 낮은 반사율을 얻을 수 있었다. 이는 일반적인 텍스쳐링과 anti-reflection coating을 거친 웨이퍼의 반사율보다 낮은 결과이다.

• Tribology and Lubricants
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• 제38권5호
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• pp.191-198
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• 2022

With the world's fast expanding energy usage comes a slew of new issues. Because one-third of energy is lost in overcoming friction, tremendous effort is being directed into minimizing friction. Surface texturing is the latest surface treatment technology that uses grooves and dimples on the friction surface of the machine to significantly reduce friction and improve wear resistance. Despite the fact that many studies on this issue have been conducted, most of them focused on parallel surfaces, with relatively few cases of converging films, as in most sliding bearings. This study investigated the lubrication performance of surface-textured inclined slider bearings. We analyzed the continuity and Navier-Stokes equations using a commercial computational fluid dynamics code, FLUENT. The results show the pressure and velocity distributions and the lubrication performance according to the number and orientation of rectangular dimples. Partial texturing somewhat improves the lubrication performance of inclined slider bearings. The number of dimples with the maximum load-carrying capacity (LCC) and minimum friction is determined. When the major axis of the dimple is arranged in the sliding direction, the LCC and friction reduction are maximized. However, full texturing significantly reduces the LCC of the slider bearing and increases the flow rate. The results have the potential to improve the lubrication performance of various sliding bearings, but further research is required.

• 한국세라믹학회지
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• 제46권6호
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• pp.685-688
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• 2009

Surface Texturing is very important process for high cell efficiency in crystalline silicon solar cell. Anisotropic texturing with an alkali etchant was known not to be able to produce uniform surface morphology in multi-crystalline silicon (mc-Si), because of its different etching rate with random crystal orientation. In order to reduce surface reflectance of mc-Si wafer, the general etching tendency was studied with HF/HN$O_3$/De-ionized Water acidic solution. And the surface structures of textured mc-Si in various HF/HN$O_3$ ratios were compared. The surface morphology and reflectance of textured silicon wafers were measured by FE-SEM and UVvisible spectrophotometer, respectively. We obtained average reflectance of $16{\sim}19$% for wavelength between 400 nm and 900 nm depending on different etching conditions.

• Tribology and Lubricants
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• 제25권3호
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• pp.141-149
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• 2009

The effect of micro-cavities fabricated using laser surface texturing (LST) technique on polyoxymethylene (POM) surface was studied in terms of heat affected zone (HAZ), cavity geometry, surface roughness, deformation of cavity along with sliding cycles, and tribological characteristics. Cavity process parameters were lamp current, process time, and the stream of air used to minimize the flow of molten polymer into cavity. Especially, the deformation of cavity geometry was extensively studied to provide deep insight into morphological analysis of the cavities. Also, this paper presents the behavior of friction and wear of POM specimens as a function of sliding cycles.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1499-1500
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• 2013

• 한국정보통신학회논문지
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• 제15권11호
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• pp.2439-2443
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• 2011

태양전지를 제작하는데 실리콘기판 표면에서의 광 흡수를 증가시키기 위한 표면조직화를 위해서 염기 용액을 이용한 습식방법을 이용하여 샘플을 제작하였다. 이렇게 준비된 염기성 에칭용액을 이용한 실리콘 웨이퍼의 표면 상태를 관찰하여 광학적 특성과의 연관성을 조사하였다. 표면조직화가 표면 전체적으로 고르게 이루어진 샘플에서 반사도가 낮았으며, 광학적 특성이 좋게 나타났다. 에칭이 과도하게 일어난 샘플에서는 오히려 반사도가 증가하여 광학적 특성이 떨어지는 것을 확인 하였다.

• Tribology and Lubricants
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• 제32권5호
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• pp.147-153
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• 2016

Friction reduction between machine components is important for improving their efficiency and lifespan. In recent years, surface texturing has received considerable attention as a viable means to enhance the efficiency and tribological performance of highly sliding mechanical components such as parallel thrust bearings, mechanical face seals, and piston rings. In this study, we perform lubrication analysis to investigate the effect of dimple shapes and orientations on the lubrication characteristics of a surface textured parallel thrust bearing. Numerical analysis involves solving the continuity and Navier-Stokes equations using a commercial computational fluid dynamics (CFD) code, FLUENT. We use dimples consisting of hemispherical and different semiellipsoidal orientations for simulation. We compare pressure and streamline distributions, load capacity, friction force, and leakage flowrate for different numbers of dimples and orientations. We find that the dimple shapes, orientations, and their numbers starting from an inlet influence the lubrication characteristics. The results show that partial texturing of the bearing inlet region, and the ellipsoidal dimples with the major axis aligned along the lubricant flow direction exhibit the best lubrication characteristics in terms of higher load capacity and lower friction. The results can be used in the design of optimum dimple characteristics for parallel thrust bearings, for which further research is required.

• 한국생산제조학회지
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• 제25권6호
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• pp.410-420
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• 2016

The geometric dimension and shape of microchannels that are formed during surface texturing are widely studied for applications in flow control, and drag and friction reduction. In this research, a new method for controlling the deformation of U channels during micro-rolling-based surface texturing was developed. Since the width of the U channels is almost constant, controlling the depth is essential. A calibration procedure of initial rolling gap, and proportional-integral PI controllers and a linear interpolation have been applied simultaneously to control the depth. The PI controllers drive the position of the pre-U grooved roll as well as the rolling gap. The relationship between the channel depth and rolling gap is linearized to create a feedback signal in the depth control system. The depth of micro channels is studied on A2021 aluminum lamina surfaces. Overall, the experimental results demonstrated the feasibility of the method for controlling the depth of microchannels.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.100.2-100.2
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• 2012

Surface texturing of crystalline silicon is carried out in alkaline solutions for anisotropic etching that leads to random pyramids of about $10{\mu}m$ in size. Recently textured pyramids size gradually reduced using new solution. In this paper, we investigated that texture pyramids size had an impact on emitter property and front electrode (Ag) contact. To make small (${\sim}3{\mu}m$) and large (${\sim}10{\mu}m$) pyramids size, texturing times control and one side texturing using a silicon nitride film were carried out. Then formation and quality of POCl3-diffused n+ emitter in furnace compare with small and large pyramids by using SEM images, simulation (SILVACO, Athena module) and emitter saturation current density (J0e). After metallization, Ag contact resistance was measured by transfer length method (TLM) pattern. And surface distributions of Ag crystallites were observed by SEM images. Also, performance of cell which is fabricated by screen-printed solar cells is compared by light I-V.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.17-24
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• 2004

Surrface texturing of tribological application is another attractive technology of friction reducing. Also, reduction of friction is therefore considered to be a necessary requirement for improved efficiency of machine. In this paper attempts to investigate the effect of density for micro-scale dimple pattern using photolithography on bearing steel flat mated with pin-on-disk. We demonstrated the lubrication mechanism for a Stribeck curve, which has a relationship between the friction coefficient and a dimensionless parameter for lubrication condition. It is found that friction coefficient is depended on the density of surface pattern. It was thus verified that micro-scale dimple could affect the friction reduction considerably under mixed and hydrodynamic lubrication conditions from based on friction map. Lubrication condition regime has an influence on the friction coefficient induced the density of micro dimple.