DUAL ELECTRON WAVE-GUIDE DEVICES - THE QUEST FOR ELECTRON DIRECTIONALCOUPLING

In our quest to demonstrate electron directional coupling, the coheren t tunneling of electrons between two electron waveguides, we have inve stigated split-gate dual electron waveguide devices. With the structur e biased in a ''leaky'' electron waveguide configuration we have carri ed out extensive observations of one-dimensional (1D) to two-dimension al (2D) tunneling between a waveguide and a neighboring two-dimensiona l electron gas. These tunneling spectroscopy experiments have provided the first glimpse of the one-dimensional density of states of a 1D el ectronic system. We have also carried out experimental observations of 1D to 1D tunneling between two electron waveguides. Demonstrating ele ctron directional coupling will still require the development of a new generation of ultrashallow heterostructures with sharp confining pote ntial barriers.