PROGRESS ON SILICON WAFER TEXTURING BY HYBRID LASER-ETCHING-PROCESS

摘要

A two-stage texturing process is applied to monocrystalline silicon wafers, diamond-wire and slurry sliced. The pre-conditioning of the surface is performed by ultra-short pulsed laser radiation. The texturisation is generated by a subsequent wet-chemical alkaline etching step. The surface structure formed by the hybrid process is investigated by scanning electron microscopy and reflectivity measurements. The influence of fluence, focus diameter, spot overlap and wavelength on the surface properties is studied. The generated surface structure changes with increasing fluence and spot overlap. For the largest spot overlap, applied in the presented work, a pyramidal structure is formed. It is found that this effect correlates with the accumulation of heat. In addition, a high reduction of the reflectivity at the surface is observed for a large spot overlap. The results indicate a high potential of the investigated hybrid process to generate texturisations which lead to a high light trapping. That is one important aspect for the use of diamond-wire slicing in production of silicon solar cell.