Fabrication of a gated gallium arsenide heterostructure resonant tunneling diode

Abstract

Techniques used to fabricate a gated resonant tunneling diode (GRTD) are presented. Molecular-beam epitaxy (MBE), image reversal contact photolithography, liftoff metallization, anisotropic reactive ion etching, isotropic liquid etching, and a resulting self-aligned gate metal deposition technique were used to realize this effort. The physical sizes of the fabricated GRTDs were 2, 4, and 6 μm in diameter. The electrical size of the channel within the vertical resonant tunneling diode, however, was controlled by a simple, self-aligned rectifying electrode at the well region. Arrays of devices were fabricated to enhance detection while retaining small geometries. The results from these first devices indicate that an in situ transition from a two-dimensional resonant tunneling diode (RTD) to a zero-dimensional quantum dot is feasible using this design. Improvements in the design are realizable from straightforward modifications in the MBE material.