Taming Tunnelling En Route to Mastering Mesoscopics

A single tunnel barrier in an asymmetric doping environment exhibits some superior properties as a microwave detector diode, when compared with any competing device. The manufacturability of even this simple structure is not yet established. One cannot yet procure semiconductor epitaxial material that routinely meets the tight tolerances on the specification required to produce diodes with a sufficiently small spread of dc I–V and microwave characteristics. Wafer-scale uniformity and wafer-to-wafer reproducibility are key issues, as are the techniques used for qualifying wafers. Proposals for devices that exploit mesoscopic systems will appear all the more realistic if tunnelling devices are established as manufacturable.