Modeling and characterization of direct tunneling hole current through ultrathin gate oxide in p-metal-oxide-semiconductor field-effect transistors

We report the calculation of hole direct tunneling (DT) current from the inversion layer in a p-metal-oxide-semiconductor field-effect transistor based on a solid physical background. Our results are in good agreement with those obtained from carrier separation measurements over a wide range of oxide thicknesses in the ultrathin regime. The effect of valence band mixing on hole quantization in an inversion layer in a Si substrate is properly accounted for by an improved one-band effective mass approximation. A modified Wentzel-Kramers-Brillouin approximation to calculate the hole transmission probability is used by adopting a more accurate dispersion equation in the oxide gap. Our method:is general, simple, and computationally efficient. It may even be used to calculate the hole DT current in other gate dielectric materials. (C) 2001 American Institute of Physics.