Field emission from selectively regrown GaN pyramids

Summary form only given. Field emission is the phenomena by which electrons quantum mechanically tunnel into vacuum from a solid or liquid by the application of an electric field. Once in vacuum, the electron transport is not restricted by collisions with the lattice. The higher velocity of electrons in vacuum than in a crystal allows the operation of high efficiency, high speed devices such as flat-panel displays and microwave power sources. The theory of field emission was first explained correctly by Fowler and Nordheim in 1928. The ideal field emitter will have a high concentration of electrons, a low work function (or electron affinity), and an atomic-sized tip. A sharp tip is necessary to provide high field near the surface yet avoid arcing. Tips in molybdenum have been deposited, and tips in silicon have been etched. Work in GaN has focused on selective-area epitaxial regrowth of the tips on a patterned GaN layer. Recently, the first observation of field emission from GaN was reported. The sharpness of the tips, the hardness of the material, and the large uniform arrays that can be produced by regrowth make GaN an excellent candidate for a viable field emission cathode.