Temperature-dependent Fowler-Nordheim electron barrier height in SiO₂/4HSiC MOS capacitors

Abstract

This paper reports on the physical and temperature-dependent electrical characterizations of the oxide/semiconductor interface in MOS capacitors with a SiO₂ layer deposited on 4H-SiC using dichlorosilane and nitrogen-based vapor precursors. The capacitors, subjected to a standard post deposition annealing process in N₂O, exhibited an interface state density Dit ≈ 9.0 × 10¹¹ cm⁻² eV⁻¹ below the conduction band edge. At room temperature, a barrier height (conduction band offset) of 2.8 eV was observed, along with the presence of negative charges in the insulator. The SiO₂ insulating properties were evaluated by studying the experimental temperature-dependence of the gate current. In particular, the temperature-dependent electrical measurements showed a negative temperature coefficient of the Fowler-Nordheim electron barrier height (dΦB/dT = − 0.98 meV/°C), which was very close to the expected value for an ideal SiO₂/4H-SiC system and much lower compared to the values reported for thermally grown SiO₂. This smaller dependence of ΦB on the temperature and the increase of the current level with temperature in the transcharacteristics measured in the relative fabricated MOSFETs represents a clear advantage of our deposited SiO₂ for the operation of MOSFET devices at high temperatures.

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ORCID for Marilena Vivona: orcid.org/0000-0002-0765-8556

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