Step tunneling-enhanced hot-electron injection in vertical graphene base transistors

This paper presents promising current-voltage characteristics of semiconductor-insulator-graphene tunnel diodes as the hot-electron injection unit in graphene base transistors (GBTs). We propose that by using a bilayer tunnel barrier one can effectively suppress the defect mediated carrier transport while enhancing the hot-electron emission through Fowler-Nordheim tunneling (FNT) and step tunneling (ST). A stack of TmSiO/TiO₂ (1 nm/ 5.5 nm) is sandwiched between a highly doped Si substrate and a single layer graphene (SLG) as the electrodes. This tunnel diode exhibits high current with large nonlinearity suitable for the application in GBTs.