PHYSICS AND DEVICE DESIGN OF VACUUM INTEGRATED CIRCUITS (CATHODES).

Abstract

A general schematic method is developed for modeling the fundamental parameters of vacuum integrated circuits (VIC's), a new class of microelectronics devices. A summary of the history of thermionic integrated circuits (TIC's) is presented, along with a discussion of the heater and its effect on device performance. The effects of the base metal on the emission properties of cathodes which are a mixture of the emission carbonates and negative photo-resist are also considered. The amplification factor is determined by using either a first or second order model depending on the desired degree of accuracy. The transconductance and anode resistance may be calculated as well by using the perveance model of cathode current. The voltage scaling factor used in the design of small voltage operating devices is applied to the analysis of planar devices. Electrostatic interactions between devices are important in the design of vacuum integrated circuits. The percent interaction function is used to quantify the effects of DC and small signal electrostatic interactions. The effect of work function differences on the DC biasing of circuits is also considered. The pseudo-radial electrostatic (PREF) lens is used to direct the electrons in a quasi-circular orbit from cathode to anode. The PREF lens is utilized in designing a series of planar devices including current source, triode (diode), enhancement-mode and depletion-mode type devices. The theory and experimentally determined characteristics of these devices are presented in detail.