Features of carrier tunneling between the silicon valence band and metal in devices based on the Al/high-K oxide/SiO2/Si structure

Abstract

The features of electron tunneling from or into the silicon valence band in a metal–insulator–semiconductor system with the HfO₂(ZrO₂)/SiO₂ double-layer insulator are theoretically analyzed for different modes. It is demonstrated that the valence-band current plays a less important role in structures with HfO₂(ZrO₂)/SiO₂ than in structures containing only silicon dioxide. In the case of a very wide-gap high-K oxide ZrO₂, nonmonotonic behavior related to tunneling through the upper barrier is predicted for the valence-band–metal current component. The use of an insulator stack can offer certain advantages for some devices, including diodes, bipolar tunnel-emitter transistors, and resonant-tunneling diodes, along with the traditional use of high-K insulators in a field-effect transistor.