• 한국태양에너지학회:학술대회논문집
• /
• 2012.03a
• /
• pp.243-247
• /
• 2012

The paper focuses on an anti-reflection (AR) coating deposited by PECVD in silicon solar cell fabrication. AR coating is effective to reduce the reflection of the light on the silicon wafer surface and then increase substantially the solar cell conversion efficiency. In this work, we carried out experiments to optimize double AR coating layer with silicon nitride and silicon oxide for the silicon solar cells. The p-type mono crystalline silicon wafers with $156{\times}156mm^2$ area, 0.5-3 ${\Omega}{\cdot}cm$ resistivity, and $200{\mu}m$ thickness were used. All wafers were textured in KOH solution, doped with $POCl_3$ and removed PSG before ARC process. The optimized thickness of each ARC layer was calculated by theoretical equation. For the double layer of AR coating, silicon nitride layer was deposited first using $SiH_4$ and $NH_3$, and then silicon oxide using $SiH_4$ and $N_2O$. As a result, reflectance of $SiO_2/SiN_x$ layer was lower than single $SiN_x$ and then it resulted in increase of short-circuit current and conversion efficiency. It indicates that the double AR coating layer is necessary to obtain the high efficiency solar cell with PECVD already used in commercial line.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.12
• /
• pp.821-825
• /
• 2015

Anti-reflective (AR) thin film was fabricated on a glass substrate by sol-gel method. The coating solution was synthesized with TEOS (tetraethlyorthosilicate) and poly ethylene glycol (PEG, 4.0 wt%). As the withdrawal speed of coating was changed from 0.1 mm/sec to 0.3 mm/sec, the thickness and refractive index of prepared thin films were changed. The reflectance and transmittance of coating glass fabricated by the withdrawal speed of 0.1 mm/sec were 0.62% and 95.0% in visible light range. The refractive index and thickness of single layer thin film were n= 1.29 and ca. 99.0 nm.

• 한국태양에너지학회:학술대회논문집
• /
• 2012.03a
• /
• pp.237-242
• /
• 2012

At present, crystalline solar cells take up a significant percentage of the solar industry. The ways of increasing the efficiency of crystalline solar cell are texturing and AR(Anti-Reflection) coating, and the purpose of these technologies is to increase the amount of available light on the solar cell by reducing the reflectivity. The reflectance of crystalline silicon solar cell combined with such technologies will be able to predict using the proposed simulation in this paper. The simulation algorithm was made using MATLAB, and it is a combination of the theories of reflection in textured wafer and in anti-reflection coated wafer. The simulation results were divided into three wavelength band and were compared with actual reflectance measured by a spectrometer. The wavelength band from 300 to 380 was named ultraviolet region and the wavelength band from 380 to 780 is named visible region. Finally, the wavelength band from 780 to 1200 named infrared region. When compared with measured reflection data, the simulation results had a small error from 0.4 to 0.5[%] in visible region. The error occurred in the rest two regions is larger than visible region. The extreme error occurred the infrared region is due to internal reflection effect, but in the ultraviolet region, the rationale on reduction phenomenon of reflectance occurred in small range did not proved. If these problem will be solve, this simulation will have high reliability more than now and be able to predict the reflectance of solar cells.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.5
• /
• pp.206-213
• /
• 2015

An omni-directional, graded-index and textured ZnO nanorods with $MgF_2$ anti-reflective(AR) coating films for the electro optical tracking system(EOTS) by e-beam evaporation method are presented. we achieved that the graded index structure can minimize image tracking interference of EOTS which is comparable to a general AR coating films. Optimized ZnO nanorods with $MgF_2$ AR coating films lead to decreasing Fresnel reflection by gradient refractive index. According to our experiment results, ZnO nanorods with $MgF_2$ AR coating films can be used for various electro optical system to improve the optical performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.200-201
• /
• 2008

태양전지 제작 시 반사방지막(Anti-reflection Coating)이 태양전지 효율에 미치는 영향을 알아보기 위한 실험으로 최적의 가스비를 알아보기 위하여 Plasma Enhanced Chemical Vapor Deposition(PECVD)를 이용한 Silicon nitride 증착 실험이다. SiH4 가스를 45 sccm으로 고정시킨 상태에서 NH3를 25,45,60,90,135 sccm으로 가변하여 Carrier Lifetime과 Refractive index를 측정하였다. PECVD의 조건은 기판온도 $450^{\circ}C$, Chamber 압력 1 Torr, 증착두께 $1000\AA$으로 고정하였다. 증착 후 500, 600, 700, $800^{\circ}C$로 열처리를 하고나서 Carrier Lifetime을 측정하여 열처리에 대한 효과도 알아보았다.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.30A no.10
• /
• pp.33-40
• /
• 1993

A reflection type 16x8 S-SEED array from LP(Low Pressure)-MODVD-grown GaAs/AlGaAs extremely shallow quantum well(ESQW) structures, with 4% Al fraction, has been fabricated. Its intrinsic region consists of 50 pairs of alternating 100.angs. GaAs and 100.angs. $Al_{0.04}$Ga$_{0.96}$As layers. A multilayer reflector stack of $Al_{0.04}$/Ga$_{0.96}$ As(599$\AA$)/AlAs(723$\AA$) was incorporated for the reflection plane below the p-i-n structures. The device processing after the MOCVD growth includes the mesa etching, isolation etching, insulator deposition, p & n metallization, and AR(Anti-Reflection) coating. For switching characteristics of the S-SEED in the form of p-i-n ESQW diode, the maximum optical negative resistance was observed at 856nm. Reflectance measurements showed a change from 15.6% to 43.3% for +0.9V to -6V bias. The maximum contrast ration of the S-SEED array was 2.0 and all the 128 devices showed optical bistability with contrast ratios over 2.4 at 5V reverse bias.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.1
• /
• pp.40-47
• /
• 2014

In this paper, $Al_2O_3$ film deposited by thermal atomic layer deposition (ALD) with diluted $NH_4OH$ instead of $H_2O$ was suggested for passivation layer and anti-reflection (AR) coating of the p-type crystalline Si (c-Si) solar cell application. It was confirmed that the deposition rate and refractive index of $Al_2O_3$ film was proportional to the $NH_4OH$ concentration. $Al_2O_3$ film deposited with 5 % $NH_4OH$ has the greatest negative fixed oxide charge density ($Q_f$), which can be explained by aluminum vacancies ($V_{Al}$) or oxygen interstitials ($O_i$) under O-rich condition. $Al_2O_3$ film deposited with $NH_4OH$ 5 % condition also shows lower interface trap density ($D_{it}$) distribution than those of other conditions. At $NH_4OH$ 5 % condition, moreover, $Al_2O_3$ film shows the highest excess carrier lifetime (${\tau}_{PCD}$) and the lowest surface recombination velocity ($S_{eff}$), which are linked with its passivation properties. The proposed $Al_2O_3$ film deposited with diluted $NH_4OH$ is very promising for passivation layer and AR coating of the p-type c-Si solar cell.

• New & Renewable Energy
• /
• v.2 no.2 s.6
• /
• pp.4-8
• /
• 2006

Reduction of optical losses in crystalline silicon solar cells by surface modification is one of the most important issues of silicon photovoltaics. Porous Si layers on the front surface of textured Si substrates have been investigated with the aim of improving the optical losses of the solar cells, because an anti-reflection coating and a surface passivation can be obtained simultaneously in one process. We have demonstrated the feasibility of a very efficient porous Si AR layer, prepared by a simple, cost effective, electrochemical etching method. Silicon p-type CZ (100) oriented wafers were textured by anisotropic etching in sodium carbonate solution. Then, the porous Si layer were formed by electrochemical etching in HF solutions. After that, the properties of porous Si in terms of morphology, structure and reflectance are summarized. The surface morphology of porous Si layers were investigated using SEM. The formation of a porous Si layer about $0.1{\mu}m$ thick on the textured silicon wafer result in an effective reflectance coefficient Reff lower than 5% in the wavelength region from 400 to 1000nm. Such a surface modification allows improving the Si solar cell characteristics.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.183-186
• /
• 2006

Reduction of optical losses in crystalline silicon solar cells by surface modification is one of the most important issues of silicon photovoltaics. Porous Si layers on the front surface of textured Si substrates have been investigated with the aim of improving the optical losses of the solar cells, because an anti-reflection coating and a surface passivation can be obtained simultaneously in one process. We have demonstrated the feasibility of a very efficient porous Si AR layer, prepared by a simple, cost effective, electrochemical etching method. Silicon p-type CZ (100) oriented wafers were textured by anisotropic etching in sodium carbonate solution. Then, the porous Si layer were formed by electrochemical etching in HF solutions. After that, the properties of porous Si in terms of morphology, structure and reflectance are summarized. The surface morphology of porous Si layers were investigated using SEM. The formation of a porous Si layer about $0.1{\mu}m$ thick on the textured silicon wafer result in an effective reflectance coefficient $R_{eff}$ lower than 5% in the wavelength region from 400 to 1000nm. Such a surface modification allows improving the Si solar cell characteristics.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.309-309
• /
• 2013

기존의 CIGS 태양전지는 window 층(GZO/ZnO/CdS)에서의 투과 및 반사 손실을 줄이기 위하여 MgF2를 이용한 AR (Anti Reflection) 층을 적용하여 cell을 제작하고 있다. 현재 단위공정을 줄이고 시간적 경제적 비용을 절감하기위해 무반사 코팅층 없이 표면의 구조를 변화 시키거나 CIGS 태양전지의 window 층만으로 cell 구조에 적용하는 연구가 많이 진행되고 있다. 본 연구는 AR층과 window층 역할을 동시에 만족하는 일체화된 window층 두께를 설계하고 성장한 후, window층의 열처리 전후의 구조적, 광학적 및 전기적 특성을 비교 평가하였다. Macleod simulation을 이용하여 window 층을 설계한 후, RF magnetron sputtering법을 이용하여 상온성장 시킨 후 N2 분위기에서 후열처리 조건에 따른 박막의 구조적, 전기적 및 광학적 특성을 변화를 X-ray diffractometer, Field emission-scanning electron microscope, Atomic force microscopy, 4 point probe, Hall 측정, 투과도 및 반사도등으로 비교 평가하였다.