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In this paper, we study the influences of a channel source-end potential profile on the ballistic transport of carriers in Si metal oxide semiconductor field effect transistors (MOSFETs) based on a quantum-corrected Monte Carlo device simulation. As a result, we found that higher ballistic efficiency is expected in MOSFETs with a heterojunction bottleneck barrier, such as Schottky source/drain MOSFETs, compared to that with the conventional p-n junction source and drain. Such a superior ballistic behavior is demonstrated due to the narrower bottleneck potential profile formed at the source-channel interface.

In this paper, we study tunneling current properties through SiO2 gate oxides in Si metal-oxide-semiconductor field-effect transistors (MOSFETs) by applying a first principles method based on the density-functional theory and nonequilibrium Green’s function approach. We employed three structural models of SiO2 layers, which are β-quartz, β-cristobalite, and β-tridymite. As a result, we found that the β-cristobalite and β-tridymite models indicate similar tunneling current properties, while the β-quartz model predicts a substantially lower tunneling current. Further, the largest tunneling current is obtained for the β-tridymite SiO2 model, which is consistent with bandstructure parameters estimated for bulk SiO2 crystals. Therefore, electronic properties of bulk SiO2 crystals can still be important for tunneling current analysis in the nanoscale range of oxide thickness.