Local transport and trapping issues in Al2O3 gate oxide structures

The bias dependence of interfacial barriers in Al2O3-based metal–oxide–semiconductor structures was studied by ballistic electron emission spectroscopy. Strong image force reductions of the barriers were observed. A conduction band offset between Al2O3 and Si of 2.78 eV was obtained. Electron trapping into levels that overlap the Si band gap and are located near the Si–Al2O3 interface led to charge densities of ∼2.5×1012 cm−2.