NOVEL GAAS-BASED SINGLE-ELECTRON TRANSISTORS WITH SCHOTTKY INPLANE GATES OPERATING UP TO 20 K

In an attempt to enhance the operation temperature of GaAs-based singl e-electron transistors (SETs), a novel Schottky in-plane gate (IPG) SE T based on voltage-controlled depletion of two-dimensional electron ga s (2DEG) was proposed, fabricated and characterized. For device fabric ation, EB lithography and the in-situ electrochemical process were app lied to a MBE-grown AlGaAs/GaAs 2DEG wafer, and narrow Pt IPGs with 20 0 nm length were realized on the side walls of 2DEG. The fabricated SE Ts clearly showed Coulomb oscillations with a Coulomb gap and Coulomb staircase at low temperatures. Coulomb oscillation was observed up to 20 K which is much higher than the operation temperature of split gate devices having similar dimensions of several hundred nm. The small. c apacitance values as well as the observed strong bias dependences of d evice characteristics are explained in terms of the depletion characte ristics of 2DEG with the Schottky IPG. The current leakage within the Coulomb gap is compatible with the cotunneling theory.