Depth-Resolved Study of the SiO2- SiC Interface Using Low-Energy Muon Spin Rotation Spectroscopy

In this work, the interface between 4H-SiC and thermally grown SiO2 is studied using low energy muon spin rotation (LE-μSR) spectroscopy. Samples oxidized at 1300 °C were annealed in NO or Ar ambience and the effect of the ambience and the annealing temperature on the near interface region is studied in a depth resolved manner. NO-annealing is expected to passivate the defects, resulting in reduction of interface traps, which is confirmed by electrical characterization. Introduction of N during annealing, to the SiC matrix, results in a thin, carrier rich region close to the interface leading to an increase in the diamagnetic asymmetry. Annealing in an inert environment (Ar) seems to have much lesser impact on the electrical signal, however the μSR shows a reduced paramagnetic asymmetry, indicating a narrow region of low mobility at the interface.