Field emission from quantum structures and concepts for suitable microwave circuit structures

Field emission from quantum structures are based on the various modified energy valleys in momentum space for semiconductors which can be demonstrated by employing the slopes of the measured Fowler-Nordheim functions. The materials the are used in this study are wide bandgap semiconductors such as GaN, AlN, AlGaN and others. Photoelectrochemical etching was used for structurization to fabricated structures such as nanostructures. The photo-assisted field emission improves the application of the new spectroscopy method. This new spectroscopy method is so applicable to investigate new quantum structures with their discrete energies. Concepts for suitable microwave circuit structure is represented here by klystrons where the basic requirement of their tubes with separate input and output electrodes is that space-charge waves or velocity modulation of the beam electrons are induced into the beam by either suitable capacitive or inductive electrodes. Another microwave-tube structure is represented by travelling wave tubes in that a helix or any other related slow-wave structure induces at the input side velocity modulation which goes into space charge density modulation at the end of the wave structure, where the signal is also induced as an amplified output.