Lateral current-constriction in vertical devices using openings in buried lattices of metallic discs

Vertical channels in semi-insulating GaAs were realized by epitaxial overgrowth over lattices of W discs, including nXn vacant positions. The Schottky depletion around the metallic inclusions is responsible for the semi-insulating behavior, and, thus, conducting channels may be created in designed openings in the lattice. By measuring the current transport in, structures with varying sizes of the channels, we demonstrate that the current is actually restricted to floating through the vacant positions. We further buried the metal discs, including openings, 60 nm above a resonant tunneling structure, and measured a negative differential resistance, with peak currents scaling with the opening area. These experiments demonstrate the effective combination of semiconductor heterostructures and embedded metal features for submicron, vertical injection into a heterostructure device. (C) 1997 American Institute of Physics. [S0003-6951(97)02445-5].