Evaluation of Spatial Distribution of Hole Traps Using Depleted Gate MOSFETs

The distribution of hole traps in the gate oxide of metal-oxide-semiconductor field effect transistors (MOSFETs) is evaluated with capacitance-voltage measurements using depleted polysilicon gate MOSFETs. Nonavalanche hole injection from the substrate shows that the average distance of hole traps from the SiO2/Si-substrate interface is 3.7 nm for MOSFETs with a 10-nm gate oxide. The experiment of a Fowler-Nordheim electron injection after the hole injection indicates that electron traps created during the hole injection exist at a distance in the range of 2.5-6 nm from the SiO2/Si-substrate interface, suggesting that hole traps also exist in the same region.