Applied Research in Thin-Film Field-Emission Tubes

摘要

Results of a long-range research and development program on micron-size field-emission devices, a unique class of active elements based on the ideas of K. R. Shoulders, are covered herein. In essence, this kind of device consists of a multilayer metal and dielectric film sandwich having a submicron-diameter vacuum cavity within which field emission is drawn and controlled by the application of voltages in the 10 to 100 V range to the metal films. The I-V characteristics of such elements are sharply exponential, making them ideal for high-speed binary logic; moreover, they may also prove useful for linear circuit applications. These elements can be produced solely out of refractory materials, e.g., molybdenum and aluminum oxide films, with the latter serving primarily for interelectrode spacing. Thus, these devices should withstand exposure to relatively high levels of temperature, acceleration, and nuclear radiation. Two techniques were developed for producing field-emitting protuberances at the bases of micron-diameter cavities in molybdenum/alumina/molybdenum film sandwiches on sapphire substrates, thus solving a major problem and permitting the measurement of basic operational characteristics that indicate the practicality of micron-size devices. (Author)