Porous silicon used as an oxide diffusion mask to produce a periodic micro doped n⁺⁺/n regions

Abstract

The realization of screen‐printed contacts on silicon solar cells requires highly doped regions under the fingers and lowly doped and thin ones between them. In this work, we present a low‐cost approach to fabricate selective emitter (n++/n doped silicon regions), using oxidized porous silicon (ox‐PS) as a mask. Micro‐periodic fingers were opened on the porous silicon layer using a micro groove machining process. Optimized phosphorous diffusion through the micro grooved ox‐PS let us obtain n++ doped regions in opened zones and n doped large regions underneath the ox‐PS layer. The dark I‐V characteristics of the obtained device and Fourier transform infrared (FTIR) spectroscopy investigations of the PS layer show the possibility to use PS as a dielectric layer. The Light Beam Induced Current (LBIC) mapping of the realized device, confirm the presence of a micro periodic n++/n type structure. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)