This paper demonstrates how sodium enhanced oxidation of Si face 4H-SiC results in removal of near-interface traps at the SiO2∕4H-SiC interface. These detrimental traps have energy levels close to the SiC conduction band edge and are responsible for low electron inversion channel mobilities (1–10cm2∕Vs) in Si face 4H-SiC metal-oxide-semiconductor field effect transistors. The presence of sodium during oxidation increases the oxidation rate and suppresses formation of these near-interface traps resulting in high inversion channel mobility of 150cm2∕Vs in such transistors. Sodium is incorporated by using carrier boats made of sintered alumina during oxidation or by deliberate sodium contamination of the oxide during the formation of the SiC∕SiO2 interface.
We introduce a new experimental setup with a biasing circuit and computer control for electrical power regulation under reversing polarity in Pt microwires with dimensions of 1×10 μm(2). The circuit is computer controlled via a data acquisition board. It amplifies a control signal from the computer and drives current of alternating polarity through the sample in question. Time-to-failure investigations under DC and AC current stress are performed. We confirm that AC current stress can improve the life time of microwires at least by a factor of 10(3) compared to the corresponding time-to-failure under DC current stress.
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