Activation mechanisms in sodium-doped Silicon MOSFETs

TL;DR

This study investigates how sodium ions in silicon MOSFETs influence conductivity, revealing impurity band splitting and electron activation processes, with implications for understanding impurity effects in semiconductor devices.

Contribution

It provides new insights into impurity band structure and electron activation mechanisms in sodium-doped silicon MOSFETs, suggesting the presence of Hubbard bands.

Findings

Impurity band splits into lower and upper bands.

Electrons activate from upper to conduction band.

Activation from lower to upper band observed.

Abstract

We have studied the temperature dependence of the conductivity of a silicon MOSFET containing sodium ions in the oxide above 20 K. We find the impurity band resulting from the presence of charges at the silicon-oxide interface is split into a lower and an upper band. We have observed activation of electrons from the upper band to the conduction band edge as well as from the lower to the upper band. A possible explanation implying the presence of Hubbard bands is given.