| The subject of vacuum microelectronics has grown dramatically in recent years since field emitter arrays (FEAs) promise a variety of applications such as flat panel displays, miniaturized rf amplifiers and bright electron sources. FEAs can now be built with microfabrication technologies used for integrated circuits. In this study, the effects of space charge, of emitter materials and of the geometric structure on the electron emission processes in field emitter arrays have been theoretically investigated.;Universal current-voltage characteristics are constructed by using a one dimensional model, showing the transition from the non space charge limited flow to Child-Langmuir space charge limited flow. These curves are normalized to the intrinsic scales that are constructed from the Fowler-Nordheim (F-N) coefficients A, B and the field enhancement factor. They provide an immediate assessment of the importance of space charge effects, once the applied voltage, effective electrode gap spacing, F-N coefficients, and the field enhancement factor are specified. The result predicted by this analysis is found to be consistent with the experimental observation for a specific field emitter.;The general condition of space charge limited flow for both thermionic and field emission has been formulated. For the first time, we explicitly identify two types of space charge limited flow: (1) the non-zero-surface-field space charge limited flow which may be found in field emission as well as in thermionic emission, and (2) the conventional zero-surface-field space charge limited flow restricted only to thermionic emission. These two types are confirmed through the constructed current-voltage (J-V) characteristics and surface electric field-voltage (E;The intrinsic beam quality of an idealized two-dimensional field emitter is evaluated. Under the assumption that the space charge effects are negligible, we construct a scaling law for the intrinsic emittance of an isolated emitter. This scaling law takes into account the F-N emission law and the effects of local field enhancement. It is given in terms of the height and width of the emitter, anode-cathode separation and voltage drop, as well as the F-N coefficients. Typical value of the normalized emittance of the tip is 0.012 mm-mrad. |
