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Formation of Porous Textures on Si (111) Wafers by Anodic Polarization in Aqueous KOH Solution
M. Abburi, U. Jelvestam, I. Olefjord
Etching, Passivation, Porous Silicon, Texturisation, Texturization, Anodic Potential
Wafer-Based Silicon Solar Cells and Materials Technology
Subtopic: Mono- and Multicrystalline Silicon Materials and Cells
Event: 25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain
Session: 2CV.3.22
2141 - 2145
ISBN: 3-936338-26-4
Paper DOI: 10.4229/25thEUPVSEC2010-2CV.3.22
0,00 EUR
Document(s): paper


Texturing is one of the challenging tasks in order to use Si(111) orientation wafers as substrate material for solar cell due to its slow etching rate. In this paper, we present an electrochemical method to create uniform porous textures for effective light trapping on Si(111). P-type Si(111) wafers were polarized, both potentiodynamically and potentiostatically, in 2M and 4M KOH solution at temperatures ranging from room temperature to 70oC. The applied potential was varied in the range from the open circuit potential (OCP) to 50V. The etched surfaces were analyzed by XPS and SEM. In the potential range from OCP to 15 V, passivating oxide layer grows from 1 nm to 22 nm at room temperature. At potentials above 20V, strong oxygen evolution occurs and the surface starts to be pitted at steps in the crystal and defects on the surface. The pore grows and propagate into the (111) plane at increasing temperature, applied potential and etching time.