Heterodimensional Schottky metal–two-dimensional electron gas interfaces

Abstract

This article presents the results of theoretical and experimental studies of the interface between a two-dimensional electron gas (2DEG) and a Schottky metal. Such an interface is an example of a new class of heterodimensional interfaces which have unusual properties with great potential for practical applications in ultrahigh speed and ultrahigh frequency devices. The unique features of such junctions include a very small effective cross section (equal to the product of the thickness of the 2DEG and the device width) leading to a small capacitance, a large breakdown voltage because of the electric field streamlines spreading in two dimensions near the metal–2DEG interface (and in three dimensions near the metal–1DEG interface) and very large electron mobility (especially at cryogenic temperatures) because of the modulation doping. Our capacitance–voltage (C–V) calculations for a 2D-Schottky junction are in good agreement with our experimental data. We also discuss the properties of other heterodimensional systems, including a one-dimensional electron gas–Schottky metal barrier contact which could be realized using advanced lithographic and etching techniques.