Surface photovoltage and Auger electron spectromicroscopy studies of HfO2/SiO2/4H-SiC and HfO2/Al2O3/4H-SiC structures

The electronic and chemical properties of the interface region in the structures obtained by the passivation of epitaxial n-type 4H-SiC layers with bilayers consisting of a 5 nm-thick SiO₂ or Al₂O₃ buffer film and high-κHfO₂ layer were investigated. The main aim was to estimate the influence of the passivation approach on the interface effective charge density (Q_eff) from the surface photovoltage (SPV) method and, in addition to determine the in-depth element distribution in the interface region from the Auger electron spectroscopy (AES) combined with Ar⁺ ion profiling. The structure HfO₂/SiO₂/4H-SiC exhibited slightly superior electronic properties in terms of Q_eff (in the range of −10¹¹ q cm⁻²).

Highlights

► We applied contactless surface photovoltage to assess oxide/SiC interface quality.

► 5 nm-thick SiO₂film seems to be better interlayer between SiC and HfO₂ than Al₂O₃.

► Element distribution in the oxide/SiC interface was obtained from AES profiling.

► SiO₂ buffer and transition silicate nanofilms were found from AES spectra analysis.

Source: Journal of Crystal Growth

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