Wet chemical passivation of interface defects in a a SI H c Si heterojunction solar cells with randomly distributed pyramids

Abstract

WET CHEMICAL PASSIVATION OF INTERFACE DEFECTS IN a SI H c SI HETEROJUNCTION SOLAR CELLS WITH RANDOMLY DISTRIBUTED PYRAMIDS H. Angermann, J. Rappich, K. v. Maydell, E. Conrad, I. Sieber, D. Schaffarzik and M. Schmidt Hahn Meitner Institut Berlin, Kekul str.5, D 12489 Berlin Corresponding author H. Angermann, Hahn Meitner Institut Berlin HMI , Kekul str.5, D 12489 Berlin, Tel 49 30 8062 1368, Fax 49 30 8062 1333 e mail angermann helmholtz berlin.de ABSTRACT Two non destructive, very surface sensitive tech niques, the large signal field modulated surface photovoltage SPV method and pulsed photoluminescence spectroscopy PL were applied to investigate both wet chemically treated substrate surfaces and a Si c Si interfaces. In order to prepare silicon substrates with randomly distributed pyramids without surface micro roughness and native oxide contamination and to passivate them during the technological process, we investigated special combinations of wet chemical etching and cleaning procedures. Compared to conventional pre treatments, significantly lower densities surface states and recombination loss were achieved on silicon substrates textured with randomly distributed upside pyramids and on the resulting a Si c Si in terfaces after deposition. It was shown that the open circuit voltage Voc and solar cell efficiency of TCO a Si H n c Si p Al solar cells are mainly influence by the preparation induced morphology and electronic properties of substrate surface. Keywords silicon substrates, defect density, wet chemical pretreatmen