Fabrication of Si single-electron transistors with precise dimensions by electron-beam nanolithography

Determining the relationship between wire size and the electrical characteristics of a single-electron transistor (SET) can significantly shorten the development time required to make SETs practical devices. In this study, this relationship was examined by fabricating SETs with precise dimensions using electron-beam nanolithography. The high-resolution resist HSQ provided fine wire patterns with small linewidth fluctuations. Si nanowires were made by etching using HSQ patterns as amask, and then oxidized to produce SETs. The electrical characteristics were measured to determine the wire size required for making operational SETs. First, it was found that more oxidation widens the range of wire widths for which clear Coulomb blockade oscillations are observed. This is probably because more oxidation produces more oxidation-induced stress, which deepens the potential well essential for SET operation. In addition, it was experimentally confirmed that the gate capacitance is proportional to the nanowire length. These results demonstrate that SETs can be fabricated with good control of the size. (C) 2003 American Vacuum Society.