Electron waveguiding in quantum wells, voltage- induced quantum wells, and quantum barriers

Abstract

Recent experiments have produced ballistic electron transport over micron lengths in semiconductor 2-D electron gas (2DEG) systems. This has made possible the demonstration of electron devices that exhibit impressive optical like behavior.1-3 In these devices, the quantum well at the 2DEG interface acts as a slab waveguide for ballistic electron waves. We show how finite- potential heterostructure wells, homostructure voltage-induced wells, and heterostructure barriers can act as electron slab waveguides. We find that the waveguiding in all these structures is described by a single dispersion relation and can occur at energies above all band edges. The guided-mode cutoffs, electron velocity, effective mass, density of states, and ballistic current density are determined. A multiple layer theory is developed to analyze wells and barriers with arbitrary potential energy profiles. The maximum ballistic guided current flowing in a given direction for a ten-monolayer Ga0.75Al0.25As/GaAs/- Ga0.9Al0.1. As waveguide is found to be 2.3 mA/μm of waveguide width. This relatively large value suggests that interconnecting multiple ballistic electron devices through a single slab waveguide may be feasible.