Voltage gain in GaAs-based lateral single-electron transistors having Schottky wrap gates

Gain characteristics of GaAs-based lateral single-electron transistors (SETs) formed by putting two- or three-wrap gates (WPGs) on etched GaAs quantum wire were investigated in detail theoretically and experimentally. The computer simulation of potential distribution showed that the three-WPG SET allows independent control of the dot geometry and the tunneling barrier profile and that the three-gate device realizes much tighter control of the dot potential and a higher voltage gain than the two-gate device. Both two- and three-gate SETs were fabricated experimentally. These devices showed clear Coulomb blockade oscillations which were visible up to 40 K. In excellent agreement with the computer simulation, a high voltage gain of 1.3 was achieved in the three-gate SET, whereas the gain of the two-gate SET remained below unity. This is the first report on achieving a voltage gain higher than unity in III-V SETs. This field effect transistor (FET)-like lateral SET structure seems to be promising for the realization of III-V SET ultra large scale integrated circuits (ULSIs).