Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 34: Impurities/Amorphous semiconductors
HL 34.4: Vortrag
Mittwoch, 29. März 2006, 18:00–18:15, BEY 154
Investigation of spin-dependent transport in a-Si:H/c-Si solar cells with pulsed electrically detected magnetic resonance — •Jan Behrends1,2, Christoph Böhme1,3, Karsten von Maydell1, and Manfred Schmidt1 — 1Hahn-Meitner-Institut Berlin, Abt. Silizium-Photovoltaik, Berlin, Germany — 2Institut für Physik, Carl von Ossietzky Universität, Oldenburg, Germany — 3Department of Physics, University of Utah, Salt Lake City, UT, USA
Spin-coherent transport of charge carriers in heterostructure solar cells based on slightly B-doped crystalline silicon (c-Si) and strongly P-doped hydrogenated amorphous silicon (n-a-Si:H) has been investigated at different bias voltages by pulsed electrically detected magnetic resonance. The analysis of the coherent spin motion provides an insight into transport through the n-a-Si:H/c-Si heterojunction involving localised states at the interface and in a-Si:H. The experiment was carried out at T = 10 K under illumination. The photocurrent changes after a coherent electron spin resonant (ESR) excitation are superimposed by Rabi oscillations that are induced by the ESR pulse. Under reverse bias of the pn-junction a general increase of the photocurrent followed by a small decrease was observed at g = 2.005(1). This signal is assumed to originate from electron hopping through conduction band tail states. Under forward bias, the signal changes its sign and a second resonance at g = 1.999(1) with different dynamics appears in addition. Line widths, intensities, and decay time constants (also of the Rabi oscillations) were determined quantitatively and will be discussed with regard to hopping and recombination time constants.