28 August 2022 to 2 September 2022
Science and Technology Campus, University of Parma
Europe/Rome timezone
Submission deadline for Conference Proceedings extended until 3 October

Profiling defect and charge carrier density in the SiO$_2$/4H-SiC interface with Low-Energy Muons

28 Aug 2022, 15:15
15m
Aula dei Cavalieri, University Central Palace, via Università 12

Aula dei Cavalieri, University Central Palace, via Università 12

Oral Semiconductors Student Day

Speaker

Maria Mendes Martins (Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute)

Description

Silicon carbide (4H-SiC) is a wide-bandgap semiconductor with promising applications in high-power and high-frequency devices. An advantage of SiC is that it is the only compound semiconductor that has the ability to form native silicon dioxide (SiO$_2$). The performance of SiC-based devices relies heavily on interface effects. However, characterization of oxidation-induced defects - both in the oxide and the semiconductor - is still challenging.
Low-energy muon spin spectroscopy (LE-$\mu$SR) can probe regions very close to the surface and interface up to a depth of 160 nm in SiO$_2$/SiC structures and is sensitive to charge carrier and defect concentrations.

We have studied SiO$_2$/SiC interfacial systems with thermally grown and deposited oxides using LE-$\mu$SR. The thermal SiO$_2$ has higher structural order, as indicated by the undisturbed muonium (Mu$^0$) formation. However, the oxidation process leads to strain in the oxide and to band-bending at the SiC-side of the interface, which affects the SiC faces differently: i) at the (0001) Si-face the results can be explained by the depletion of electrons at the interface and ii) at the (000$\overline{1}$) C-face a carbon-rich n-type region contributes to the increase of the diamagnetic fraction due to Mu$^-$ formation.
Further investigations have been conducted to understand the passivation effects of state-of-the-art post-oxidation annealing (POA) processes on the SiO$_2$/SiC interface. Particularly, POA in an NO environment leads to an increase in charge carrier concentration near the interface, likely due to N acting as a dopant, which can be quantified based on the measured diamagnetic fraction.

Primary author

Maria Mendes Martins (Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute)

Co-authors

Mr Piyush Kumar (Advanced Power Semiconductor Laboratory) Dr Judith Woerle (Advanced Power Semiconductors) Xiaojie Ni (Paul Scherrer Institute) Prof. Ulrike Grossner (Advanced Power Semiconductors) Dr Thomas Prokscha (PSI)

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