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O: Oberflächenphysik

O 12: Grenzfl
äche fest-flüssig

O 12.5: Talk

Monday, March 26, 2001, 17:15–17:30, K

Charging at Si surfaces in fluoride solutions: an in-situ photovoltage investigation — •Joerg Rappich¹, Thomas Burke^1,2, Sandra Lust³, Claude Levi-Clement³, and Thomas Dittrich² — ¹Hahn-Meitner-Institut, Abt. Si-Photovoltaik, Kekulestr.5, D-12489 Berlin, Germany — ²Technische Universitaet Muenchen, Physik Department E16, D-85748 Garching, Germany — ³Laboratoire de Chimie Metallurgique des Terres Rares, CNRS UPR 209, 2/8 rue Henri Dunant, F-94320 Thiais, France

The charging at Si surfaces in fluoride solutions has been studied in-situ by pulsed photovoltage during electrochemical treatments. The Si surface charges positively with onset of the formation of porous silicon. A negative charging of the Si surface takes place during oxide removal in fluoride solution when the electrolyte reaches the Si surface while the negative charge is replaced during the following hydrogenation process of the Si surface. The process of negative charging / discharging is independent of the type of the removed oxide. The positive and negative charging at Si surfaces in fluoride containing electrolytes is related to the formation of surface states at intermediate chemical complexes.