Plasma texturing for silicon solar cells: From pyramids to inverted pyramids-like structures

We have studied systematically a dry and free mask texturing process of crystalline silicon wafers using SF6/O2 plasmas in a reactive ion etching (RIE) system, with special attention on the effect of the RF plasma power and the SF6/O2 ratio on the texture of the silicon surface. In particular, we have found that by increasing the RF power, with an optimized SF6/O2 ratio and pressure it is possible to switch from a random texture, to a pyramid-like texture and finally to an inverted pyramid-like texture. This resulted in average reflectance values as low as 6%, which open an exciting opportunity for crystalline silicon solar cells applications.