A detailed study of industrially compatible, cost-effective and convenient texturization in large area diamond cut n-type C-Si

摘要

Texturization of diamond cut crystalline silicon wafer faces a great difficulty due to the presence of deep saw marks on all over the wafer surface, which limits the ultimate efficiency enhancement of solar cell. Conventional slurry cut silicon anisotropic texturization is carried out by saw damage removal step with NaOH aqueous solution followed by etching with potassium hydroxide (KOH)-isopropyl alcohol (IPA) but textural result is not satisfactory after adopting diamond cut silicon texturization in conventional way. The non-uniform pyramidal surface has been observed with noticeable spots. Surface texturization of diamond cut silicon wafer has been improved after introducing a new method. Adding little amount of sodium hypochlorite (NaClO) along with KOH-IPA solution and excluding the saw damage removal step creates better textural result in 20 min compared to conventional texturization method. Minimum reflectance is observed at 9.88, whereas conventional method provides above 16 reflectance. Batch compatibility test also provides uniform texturization result up to batch 6, after which the pyramidal angle gets tilted to 4.07 degree resulting increase in reflectance to 12. Optimizing the chemical solution exhibits excellent anisotropic etching, which eventually improves silicon nanograss solar cell performance. About 14 efficiency is found for conventional texturization in diamond cut wafers, while 18.5 efficiency with 72 yield is found for our proposed method.