Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 55: Photovoltaics: Silicon-based Systems II
HL 55.3: Vortrag
Mittwoch, 28. März 2012, 11:45–12:00, ER 270
Paramagnetic defects at the interface of silicon heterojunction solar cells detected by Electrically Detected Magnetic Resonance — •Benjamin Muguluvila George1, Jan Behrends2, Tim Ferdinand Schulze1, Matthias Fehr1, Lars Korte1, Manfred Schmidt1, Alexander Schnegg1, Klaus Lips1, and Bernd Rech1 — 1Helmholtz Zentrum Berlin für Materialien und Energie — 2Freie Universität Berlin
Amorphous silicon (a-Si:H)/crystalline silicon (c-Si) heterojunction solar cells reach the highest efficiency of mass produced silicon solar cells. Due to the high quality of the silicon wafer material and low thickness of a-Si:H used, the passivation quality of interface defects ultimately determines device efficiency. Additionally this heterojunction is an instructive model system for state-of-the-art microcrystalline silicon (mu-cSi:H) solar cells as they intrinsically possess a high number of a-Si:H/c-Si interfaces at grain boundaries. In this study the spectroscopic properties of paramagnetic defects at the a-Si:H/c-Si interface are investigated by low temperature electrically detected magnetic resonance (EDMR) due to its high sensitivity and the ability to study fully processed solar cells. Spin-dependent recombination between conduction band tail states in the a-Si:H bulk and a-Si:H/c-Si interface dangling bonds is detected. By taking a rotation pattern this signal has been assigned to the a-Si:H/c-Si interface. The g-tensor of this site on the [111] oriented silicon wafer resembles the values of the well-known Pb center at the SiO2/Si interface. By way of sample preparation it can be excluded that natural SiO2 is present at the interface.