Study of porous silicon for anti-reflection applications

• Main Authors: Nguyen, Chi-Lang, 阮芝陵
• Other Authors: Chang, Yi
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/39117819980194914003

碩士 === 國立交通大學 === 材料科學與工程學系 === 98 === iii nitric acid is lower than 40% in volume, porous etching occurs. The transition between porous formation and polishing etching occurs when nitric acid content is lager than 40%. Pore size distributes uniform on the surface of wafer. Stain etching also provides the rough surface. After etching in the proper etchant solution, the reflectance of the bare wafer was reduced to 0%. We have also successfully formed porous layer in large size (7.5x7.5cm) Si (100) which has lower reflectance compared with conventional AR PECVD-Si3N4, and SiO2 .We conclude that stain etching porous silicon could be a promising replacement for the conventional AR coatings.In this dissertation, we numerically study the reflectance of porous silicon (PS) layer for antireflection applications. Based on the numerical study, we develop chemical etchant (HF, HNO3, H2O) to form PS layer on crystalline silicon wafer. As we all know, silicon nitride and silicon dioxide are well known antireflection coating used in semiconductor industry. However, the deposition of silicon nitride and silicon dioxide films increase the total cost of solar cell modules which is not suitable for low-cost photovoltaic devices. In the other hand, the chemical etching known as stain etching (SE) porous silicon is a cheap, simple and rapid technique for texturing single-crystalline silicon. In addition, porous silicon shows the remarkable low reflectance at visible light. In this study, we have successfully fabricated porous silicon layer on top of the Si (100) and Si (111) surfaces. We varied the proportion of the solution of nitric acid, hydrofluoric acid and water to optimize the etching process. We found that nitric acid plays a very important role in stain etching. When the proportion of the