The performances of an SET required for integration are discussed. Conventional SETs had several problems such as large leakage current, insufficient voltage gain and so on. To overcome these problems, a new SET utilizing Schottky barriers as tunnel junctions is proposed. Its current characteristics and Coulomb-blockade conditions are calculated and the effectiveness for an integrated device is discussed.

Various techniques of single-electron circuit simulation are presented. The subjects include visualization of state probabilities, accurate yet reasonably fast steady-state analysis and SPICE-based high-speed simulation for circuits composed of Single-Electron Transistors (SETs). The visualized state probabilities allow one to grasp the dynamics of a single-electron circuit intuitively. The new algorithm for steady-state analysis uses the master equation and Monte Carlo method in combination. We suppose this is the best way to perform steady-state analysis. The SPICE-based simulator significantly outperforms the conventional reference simulator in speed. It is, to the best of our knowledge, the only simulator that can simulate SET circuits for real applications. It also facilitates the study of the integration of SETs and MOSFETs.