Electrically Detected HYSCORE on Conduction Band Tail States in 29 Si-Enriched Microcrystalline Silicon

Abstract

Electrically detected hyperfine sublevel correlation (ED-HYSCORE) measurements are presented and employed to study spin-dependent transport in thin-film microcrystalline silicon solar cells. We explore the hyperfine coupling between paramagnetic conduction band tail states involved in hopping transport and neighboring 29Si nuclei at low temperature ( T=5 K). ED-HYSCORE measurements performed on solar cells with 29Si-enriched absorber layers reveal that the hyperfine interaction between these current-influencing centers and 29Si nuclei in the surroundings is dominated by isotropic couplings up to ∼ 4 MHz, whereas the anisotropic contributions are small. This indicates that the wave function of the conduction band tail states is distributed over several nuclei. Our results demonstrate that the ED-HYSCORE technique can provide helpful insight into the microscopic structure of transport-relevant paramagnetic states and thus usefully complement the toolbox of electrically detected magnetic resonance spectroscopy.