Ambipolar Coulomb blockade characteristics in a two-dimensional Si multidot device

A two-dimensional Si multidot channel field-effect transistor is fabricated from a silicon-on-insulator material and the electrical characteristics are studied. The multidots are formed using a nanometer-scale local oxidation of Si process developed in our laboratory. The device shows ambipolar characteristics because of Schottky source and drain, i.e., the carriers are electrons for positive gate voltage and holes for the negative one. It is shown that Coulomb blockade (CB) oscillations are clearly observed for both of the electrons and holes at measurement temperatures up to 60 K. Both CB characteristics show nonperiodic oscillation and an open Coulomb diamond. These features are ascribed to the single electron/hole tunneling in the Si multidot channel.