Electrical conduction of silicon oxide containing silicon quantum dots

Current–voltage measurements have been made at room temperature on a Si-rich silicon oxide film deposited via electron-cyclotron resonance plasma enhanced chemical vapour deposition (ECR-PECVD) and annealed at 750–1000 °C. The thickness of the oxide between Si quantum dots embedded in the film increases with increasing annealing temperature. This leads to a decreasing current density as the annealing temperature is increased. Assuming the Fowler–Nordheim tunnelling mechanism in large electric fields, we obtain an effective barrier height eff of ~0.7 ± 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 tunnelling.