The charge transport mechanism and electron trap nature in thermal oxide on silicon

TL;DR

This study investigates the charge transport mechanism in amorphous SiO₂ on silicon, revealing phonon-assisted tunneling between traps, the role of oxygen vacancies as electron traps, and how annealing affects leakage current.

Contribution

It provides detailed insights into the trap energies, charge transport process, and effects of annealing on oxygen vacancies in thermal oxide on silicon.

Findings

Electron transport is limited by phonon-assisted tunneling between traps.

Oxygen vacancies act as electron traps in SiO₂.

Annealing reduces leakage current by recombining oxygen vacancies.

Abstract

The charge transport mechanism of electron via traps in amorphous SiO$_2$ has been studied. Electron transport is limited by phonon-assisted tunneling between traps. Thermal and optical trap energies $W_\mathrm{t}=1.6$ eV, $W_\mathrm{opt}=3.2$ eV, respectively, were determined. Charge flowing leads to oxygen vacancies generation, and the leakage current increases due to the increase of charge trap density. Long-time annealing at high temperatures decreased the leakage current to initial values due to oxygen vacancies recombination with interstitial oxygen. It is found that the oxygen vacancies act as electron traps in SiO$_2$.