CONTROLLED CARRIER DEPLETION AROUND NANO-SCALE METAL DISCS EMBEDDED IN GAAS

Matrices of uncontacted, nano-scale. tungsten discs, embedded in GaAs by epitaxial overgrowth, have been characterised electrically. By vary ing the spacing between the discs, it is demonstrated that when the di sc separation is smaller than 300 nm (for a doping level of 10(16) cm( -3)), the conductance drops by seven orders of magnitude and the mater ial becomes semi-insulating. The presence of the metal-induced barrier is deduced from the temperature dependence of the current transport. These results are discussed in terms of overlapping Schottky depletion regions around the discs.