Triplet excitons as sensitive spin probes for structure analysis of extended defects in microcrystalline silicon

Christoph Meier, Christian Teutloff, Jan Behrends, Robert Bittl, Oleksandr Astakhov, Klaus Lips

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Abstract

Electrically detected magnetic resonance (EDMR) spectroscopy is employed to study the influence of triplet excitons on the photocurrent in state-of-the-art microcrystalline silicon thin-film solar cells. These triplet excitons are used as sensitive spin probes for the investigation of their electronic and nuclear environment in this mixed-phase material. According to low-temperature EDMR results obtained from solar cells with different Si29 isotope concentrations between 0.01% and 50%, the triplet excitons reside at extended defects in the crystallites of microcrystalline silicon that give rise to shallow states in the silicon band gap. The excitons possess a rather delocalized wave function, couple to electron spins in conduction band tail states nearby, and take part in a spin-dependent recombination process. Our study shows that extended defects such as grain boundaries or stacking faults in the crystalline part of the material act as charge carrier traps that can influence the material conductivity.

Original languageEnglish
Article number045302
Pages (from-to)1-13
Number of pages13
JournalPhysical Review B
Volume94
Issue number4
DOIs
Publication statusPublished - 6 Jul 2016
Externally publishedYes

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