Influence of Dopant Concentration on the Electrical Transport at Low Temperature in Silicon Nanowires

We demonstrate the correlation between the the doping atoms concentration and the Coulomb blockade phenomenon in silicon nanowires. At room and intermediate temperatures nanowires show a field effect, while at low temperature current oscillations due to Coulomb blockade dominate transport close to the conduction threshold. Detailed experimental results on samples with two different doping levels allowed Coulomb blockade to be related to the presence of the dopants. In the limit of a few dopants per cross section, as for low doping level (2.5×10¹⁷cm^-3), the electrical behavior of the nanowire is similar to that of a one dimensional array of dots. In nanowires with a high doping level (10¹⁹cm^-3), transport can be modeled on the basis of a two dimensional arrays of dots.