Coulomb blockade effects and conduction mechanism in extremely thin polycrystalline-silicon wires

Abstract

Narrow (⩾95 nm) and extremely thin (∼7 nm) heavily phosphorous-doped polycrystalline-silicon (poly-Si) wires were fabricated by low-pressure chemical vapor deposition. The electrical conduction mechanism has been investigated at low temperatures (down to ∼5 K), and observation by transmission electron microscopy (TEM) was carried out. Single-electron effects such as Coulomb oscillations have been observed at temperatures up to 80 K. The size of the island in the poly-Si wires was estimated from the electrical properties, and it was in the same order as the grain size of the poly-Si measured by TEM. A maximum tunnel barrier height of ∼26 meV of the poly-Si grain boundary is obtained from the temperature dependence of the conductance of the sample. A model for the electronic conduction through multiple islands was proposed from the width dependence of their electrical properties.