FABRICATION OF A NANOSCALE, INPLANE GATED QUANTUM-WIRE BY LOW-ENERGY ION EXPOSURE

The fabrication of a nanoscale gated quantum wire in a GaAs modulation doped field effect transistor substrate is described. Both the wire c onduction channel, with a 110 nm physical width, and the gates were pa tterned into the two-dimensional electron gas of the substrate. This s cheme produced in-plane gated devices with 110 nm gate lengths and 75 nm separations between the active areas. Electron-beam lithography was used to define masks for a subsequent flood exposure step with low en ergy argon ions (150 eV). This ion exposure technique produced very hi gh gate-to-wire isolation, typically greater than 10(14) OMEGA at 4.2 K. The in-plane design employed here drastically reduces gate capacita nce compared with metal top-gate designs, and promises ultrafast switc hing times. These devices showed no short channel punch-through effect s, exhibited low gate leakage, and had sufficient gain to permit integ ration of several such devices into more complex circuits such as logi c gates.