Surface texturing using reactive ion etching for multicrystalline silicon solar cells

Abstract

We have developed a new surface texturing technique using a reactive ion etching (RIE) method for multicrystalline silicon (mc-Si) solar cells, which is expected to form a low reflectance surface on grains of various crystalline orientations. This surface texture has a cone shape, and aspect ratio and size of which can be easily controlled. We have optimized surface shape and emitter sheet resistance. The optimum emitter sheet resistance for RIE textured cell is higher than that for the usual cell. The high aspect ratio of the cone shape makes surface reflectance low, but the cell efficiency is not so good. There is an optimum aspect ratio because the emitter of cell with high aspect ratio surface has large saturation current and cell performance is decreased with aspect ratio. We have fabricated over 17% efficient large area (225 cm/sup 2/) mc-Si solar cell using this surface texturing technique and passivation schemes which is based on the silicon nitride film deposited by the plasma CVD method and hydrogen annealing at a high temperature.