SELF-CONSISTENT MODELING OF ACCUMULATION LAYERS AND TUNNELING CURRENTS THROUGH VERY THIN OXIDES

Poisson and Schrodinger equations are solved self-consistently for acc umulated layers in metal-oxide-semiconductor devices and applied to th e calculation of tunneling currents at 300 K and 77 K and extraction o f parameters for very thin oxides. Calculations at 300 K show strong a greement with measured tunneling currents and also point out the sourc es of inaccuracies in extracting thicknesses of oxides by electrical m ethods such as through measurement of capacitance. Direct tunneling cu rrent in thin oxides (1.5-2.0 nm) are shown to achieve larger than 1 A /cm(2) current density for applied voltages smaller than 3 V, pointing to possibilities of achieving high endurance injection across thin ox ides. Comparison of calculations using a classical approach and self-c onsistent approach shows fortuitous agreements in tunneling currents d espite large differences in the physical models. Appropriate methods f or calculating tunneling currents from bound and extended quantum stat es are also described. (C) 1996 American Institute of Physics.