Abstract
Silicon oxycarbide (SiCxOy), commonly used as low-κ inter layer dielectric in technological applications, is limited in performance due to dielectric breakdown in the presence of defect states. In this work, chemical vapour deposition technique has been used to fabricate carbon rich SiCxOy−n-silicon heterojunction using liquid polycarbosilane as precursor. The heterojunctions showed Schottky diode like behaviour with high current rectification (28k at ± 5 V) and high breakdown voltage (−100 V). Localised defect states originated from free residual carbon in deposited films, arising between valance band maxima and Fermi level of the oxycarbide, were found to be responsible for Schottky diode nature of the fabricated devices. A comprehensive band diagram of the heterojunction, alongside an insight of charge transport process, is presented based on valance band edge spectroscopy and temperature dependent transport measurements. A crossover between Zener and avalanche like soft breakdown was observed in our devices from which effective band gap of the oxycarbide films have been estimated. The devices showed excellent performance stability and reproducibility against rapid cyclic voltage sweep in ambient condition. Stability and performance reproducibility of the heterojunctions were remarkably maintained even after two years of storage in ambient condition that has long term implication in power electronics.
Published Version
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