POLYCRYSTALLINE SILICON-WAFER ENGINEERING FOR PHOTOVOLTAIC APPLICATIONS

A mechanical dicing saw in combination with bevelled blades has been u sed to create a variety of textured structures in cast photycrystallin e silicon, ribbon, and also single crystalline material far photovolta ic applications. It is shown that the mechanical grooving step may be applied consecutively to both the front and the back surfaces of a sil icon blank. The independence of this method with regard to crystal ori entation together with a variable blade tip angle represents a hithert o unknown freedom of poly-Si solar cell design. Flexible textured foil s with a minimum silicon thickness of 20 mu m are demonstrated. This i s an important prerequisite for the preparation of highly efficient so lar cell structures in finely grained polycrystalline sheets with diff usion lengths smaller than 50 mu m.