This paper builds on previous work that has demonstrated that interfacial suboxide transition regions at Si-SiO2 interfaces modify tunneling oscillations in the Fowler-Nordheim regime. This paper extends this approach to the direct tunneling regime, emphasizing differences in interfacial transition regions between Si-SiO2 interfaces with and without monolayer level interface nitridation. Tunneling currents in devices with the same oxide-equivalent thickness are reduced by monolayer level interfacial nitrogen with respect to devices without interface nitridation for both substrate and gate injection in both the direct and Fowler-Nordheim tunneling regimes. These decreases have been combined with physically thicker stacked oxide/nitride dielectrics to yield significantly reduced tunneling compared to devices with oxides of the same equivalent oxide thickness, t(ox-eq); e.g., tunneling currents similar to 5 x 10(-3) A/cm(2) at 1 V for t(ox-eq) similar to 1.6 nm have been obtained.