Using low-energy muons, we map the charge carrier concentration as a function of depth and electric field across the \SiOSi interface up to a depth of \SI{100}{\nano\meter} in Si-based MOS capacitors. The results show that the formation of the anisotropic bond-centered muonium \MuBCz state in Si serves as a direct measure of the local changes in electronic structures. Different band-bending conditions could be distinguished, and the extension of the depletion width was directly extracted using the localized stopping and probing depth of the muons. Furthermore, electron build-up on the Si side of the \SiOO/Si interface, caused by the mirror charge induced by the fixed positive charge in the oxide and the image force effect, was observed. Our work represents a significant extension of the application of the muon spin rotation technique (μSR) and lays the foundation for further research on direct observation of charge carrier density manipulation at technologically important semiconductor device interfaces.
@article{arxiv.2405.18211,
title = {Observation and manipulation of charge carrier distribution at the SiO$_2$/Si interface},
author = {Maria M. Martins and Piyush Kumar and Marianne E. Bathen and Zaher Salman and Ulrike Grossner and Thomas Prokscha},
journal= {arXiv preprint arXiv:2405.18211},
year = {2024}
}