Reflectance Of Silicon Wafer Research Articles

Effect of Microstructures With Different Depth-to-Width Ratios on Surface Reflectance and Si Solar Cell Performance

Metal-catalyzed chemical etching (MCCE) is an effective method for making texture surface on diamond wire saw (DWS) cut mc-Si wafer. In this work, microstructures with different depth-to-width ratios were obtained by MCCE on the surface of DWS cut mc-Si wafers. Simultaneously, the influence of etching time and the concentration of AgNO3 on etching depth, surface reflectance performance, and effect of reaming on the solar cell performance were studied. In total, 12 microstructures with different depth-to-width ratios ranging from 0.63 to 5.31 were prepared. The etching rate increased with the increase in concentration of AgNO3 and etching time. Moreover, the depth-to-width ratio significantly affected the reflectivity of silicon wafers. The relationship between them can be expressed by the fitting exponential function: y = 12.41 × x −0.733. The reflectivity obtained in the experiment ranged from 3.71% to 18.15%. After reaming, the performance of the mc-Si solar cells has been significantly improved, and η could reach up to 18.53%.

Role of the spacer layer in plasmonic antireflection coatings comprised of gold or silver nanoparticles

Metal nanoparticles (NPs) can increase the absorption of light within semiconductors and hence improve the efficiency of solar cells. We experimentally investigate the effect that gold and silver NPs have on the reflectance of silicon wafers. The NPs are fabricated using the low cost, large area technique of thermal dewetting. We show that a dielectric spacer layer between the NPs and the semiconductor is required to achieve a net reduction of reflection. Furthermore, the optimum thickness of the spacer layer is found to be independent of NP size and metal type.

金刚石线锯切割多晶硅片的气相制绒研究

Vapor etching was used to etch diamond wire sawn multicrystalline silicon wafers.The vapor was produced from 2g silicon wafer adding into HF-HNO3-H2 O acid mixture solution(400mL,in the volume ratio of 6:3:1)to reaction at room temperature.Diamond wire sawn multicrystalline silicon wafers were etched in vapor.Etching for 4min,saw marks can be removed and honeycomb etched pits were densely covered with silicon wafer surface.The reflectivity of silicon wafer decreases remarkablely by using the vapor etching methods.The reflectivity of the silicon wafers by vapor etching is low to19.51%.The micro-roughness of diamond wire sawn mulicrystalline silicon wafers etched with vapor method is actually about 20% higher than that of etching with traditional acid mixture solution method.

Novel Additive for Alkaline Texturing of Mono-Crystalline Silicon

Isopropyl alcohol(IPA) is widely used as additive to enhance surface structure and reduce the reflectivity of silicon wafers in alkaline texturing process of mono-crystalline silicon solar cells currently. However, due to its low boiling point and high volatilization, some negative effects are brought into large scale production especially in stability, cost and environment. In this paper, Dipropylene glycol(DPG) which has relative high boiling point was tried to substitute IPA as texturing solution additive. The influences of concentration of DPG and NaOH on etching rate, surface morphology and reflectance spectrum were investigated. It is obviously observed that the silicon is prevented from etching reaction by the existence of DPG. The best weight reflectance of 13.6% is obtained on mono-crystalline silicon surface by an optimized solution of 1 wt% NaOH and 1 wt% DPG at 80°C for 20 minutes. Finally, the influencing mechanism of DPG was also discussed in detail.

Full Field Temperature Measurement of Specular Wafers During Rapid Thermal Processing

Many of the processes involved in the creation of semiconductor devices involve high-temperature processing of silicon wafers. The benefits of reduced thermal budget and faster cycle time make rapid thermal processing (RTP) a possible key technology for semiconductor manufacturing. However, the problem of nonuniform wafer temperature has prevented it from further spread among the industry. The first step in developing controls to maintain a uniform wafer temperature is accurate temperature measurement during processing. In this paper, a system was developed to exploit the specular reflectivity of silicon wafers and obtain a measurement of the wafer temperature profile. The spectral reflectivity is determined by measuring the intensity of an incident beam and the beam reflected from the wafer surface. With this measured reflectivity value the spectral-directional wafer emissivity was determined using Kirchhoff's law. The obtained emissivity then was used to calculate the wafer temperature profile from an image obtained with an infrared camera. An experimental study of the transmittance of an undoped silicon calibration wafer at an elevated temperature is also discussed

Measurement of Thermal Radiative Properties of Silicon Wafers with Oxide Film and Nitride Film at 950°C

The normal spectral emissivity, reflectance and transmittance of silicon wafers were measured at a temperature of 950°C and wavelengths of 0.7 to 9μm. The samples were seven silicon wafers with oxide films of 2.2 to 628nm film thickness and nitride films of 48 to 193nm film thickness with small dopant density. It was found that the emissivities of specular surfaces of silicon wafers with very thin oxide films at wavelengths of 0.7 to 8μm were 0.6 to 0.7, the reflectances were 0.1 to 0.3 and the transmittances were 0 to 0.2. The emissivity of silicon wafers with oxide films of more than 75nm film thickness and nitride films of more than 48nm film thickness changed from 0.6 to 1.0 according to film thickness and wavelength. The emissivities and reflectances of silicon wafers were calculated using the free carrier absorption theory considering the interference phenomenon. Calculated results agreed with experimental results.