We have observed single-electron charging effects in heavily doped pol
ycrystalline silicon nanowires at 4.2 K. Wires of approximately 20 nm
by 30 nm active cross section were defined by electron-beam lithograph
y and thermal oxidation in standard polycrystalline silicon material.
We have measured a Coulomb staircase and periodic current oscillations
with gate bias, attributed to localized carrier confinement resulting
from a statistical variation in the intergrain tunnel barriers. A sha
rp change in the current oscillation period is seen and we speculate t
hat it is due to electrostatic screening of the gate bias by grain bou
ndary defect states. (C) 1998 American Institute of Physics. [S0003-69
51(98)02534-0]