Enhanced carrier collection observed in mechanically structured silicon with small diffusion length

The diffusion length of minority charge carriers in the silicon bulk L-diff is an important characteristic of optoelectronic devices fabricated from l ow cost silicon wafers. In this study computer simulations have been carrie d out to calculate the beneficial effects of a macroscopic surface texturiz ation on the charge carrier generation and the collection probability. Text ured solar cells should be able to collect charge carriers more effectively resulting in an increased current due to the special emitter geometry resu lting from the texture, decreased reflection losses, and the inclined penet ration of the light. In order to prove this expected behavior, deeply V-tex tured solar cells have been processed and characterized on low cost silicon reaching an L-diff of about 25 mu m. Spatially resolved high resolution me asurements of the internal quantum efficiency exhibit a strongly increased signal in the texture tips which is the first experimental proof of the inc reased charge carrier collection probability of deeply textured solar cells . This effect can further be seen in cross sectional electron beam induced current measurements and the mechanical texture results in an overall gain in short circuit current density of about 11% and in efficiency of about 8% relatively. (C) 1999 American Institute of Physics. [S0021-8979(99)02324-5 ].