THE SURFACE TEXTURIZATION OF SOLAR-CELLS - A NEW METHOD USING V-GROOVES WITH CONTROLLABLE SIDEWALL ANGLES

The bulk recombination mechanisms (such as the Auger recombination, for instance) that prevent the collection of photogenerated carriers are determining the present tendency of designing thinner silicon solar cells. Such an evolution requires light trapping methods in order to keep the average light path to good values. Light trapping can be obtained through surface texturization. A texturization method using a HF-HNO3 solution in an isotropic etching has been investigated. This method has allowed us to obtain a surface of periodic V-grooves with controllable sidewall angles. Beside the fact that this new texturization method of silicon may lead to new light trapping structures, it also shows a simple way to texturize polycrystalline silicon solar cells. A ray tracing program has been devised in order to calculate the average light path for rays having a long wavelength (those rays being not readily absorbed by the Si substrate) and the generated photocurrent (without recombination effects) in cells with varying surface texturization angles.