Fully Quantum-Mechanical Calculation of Hole Direct Tunneling Current in Ultrathin Gate Oxide p-Channel Metal-Oxide-Semiconductor Devices

Abstract

The hole direct tunneling currents through ultrathin gate oxides have been calculated quantum-mechanically for not only bulk but also silicon-on-insulator (SOI) p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) with p+-polysilicon gates. In this work, the coupled Schrödinger and Poisson equations are solved self-consistently taking into account the wave-function penetration into the gate oxide and gate electrode completely. For bulk pMOSFETs, the experimental verification of the calculated hole tunneling current has been presented, and the effects of the wave-function penetration on quantization in the substrate have also been investigated. The hole tunneling currents in SOI pMOSFETs have been examined for various SOI layer thicknesses. Moreover, the quantum-mechanical effects on the tunneling current in ultrathin SOI pMOSFETs are discussed in detail.