Electron Emitters for Flat Panel Displays

Field emission electron sources have many attractive features. They have high brightness, are energy efficient as they require no heater, and may readily be fabricated into arrays. Field emission sources are now routinely used in high performance electron microscopes, but their largest potential application is in flat panel displays where rival technologies have difficulty matching the display quality of electrons bombarding phosphors. This presentation will therefore concentrate on display applications. There are five broad categories of emitter: arrays of individual field emission tips formed using Spindt technology or silicon micro engineering; broad-area field emitters such as diamond like carbon, carbon nanotube mats or printed composites (there is much activity in carbon-based emitters); thin film edge emitters; surface conduction emitters (SCE); and metal-oxide-metal emitters. The latter two are not strictly field emitters as they depend on a supply of hot electrons to the surface for emission. Each type has been demonstrated successfully on a small scale; the problem comes in engineering the scale-up to a commercially viable product. The most successful large area demonstrations are 36 inch displays using SCE that are now close to market. Spindt technology depends on micron resolution lithography semiconductor processing technology, effectively limiting the size of displays to less than about 20 inches. Convincing displays have been produced but have not proved economically viable at large sizes, although small displays for automotive applications are at or near market. However the main potential market for field emission displays is for larger, 30 inch plus panels for TV applications where they have potential cost and performance advantages over plasma and LCD panels