Electrical conduction of silicon oxide containing silicon quantum dots

TL;DR

This study investigates the electrical conduction mechanisms in silicon-rich silicon oxide containing silicon quantum dots, revealing how annealing temperature affects current density and identifying tunneling and Frenkel-Poole effects as key processes.

Contribution

It provides new insights into the conduction mechanisms in Si quantum dot-embedded oxide films, including effective barrier height and the role of tunneling and trap states.

Findings

Current density decreases with higher annealing temperatures.

Effective barrier height for tunneling is approximately 0.7 eV.

Both Fowler-Nordheim tunneling and Frenkel-Poole effects explain conduction.

Abstract

Current-voltage measurements have been made at room temperature on a Si-rich silicon oxide film deposited via Electron-Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition (ECR-PECVD) and annealed at 750 - 1000$ ^\circ$C. The thickness of oxide between Si quantum dots embedded in the film increases with the increase of annealing temperature. This leads to the decrease of current density as the annealing temperature is increased. Assuming the Fowler-Nordheim tunneling mechanism in large electric fields, we obtain an effective barrier height $\phi_{eff}$ of $\sim$ 0.7 $\pm$ 0.1 eV for an electron tunnelling through an oxide layer between Si quantum dots. The Frenkel-Poole effect can also be used to adequately explain the electrical conduction of the film under the influence of large electric fields. We suggest that at room temperature Si quantum dots can be regarded as traps that capture and emit electrons by means of tunneling.