Abstract
In order to realize a high-power microwave amplifier design known as a gigatron, a gated field emission array must be developed that can deliver a highintensity electron beam at gigahertz frequencies. No existing field emission device meets the requirements for a gigatron cathode. In the present work, a porous sihcon-based approach is evaluated. The use of porous silicon reduces the size of a single emitter to the manometer scale, and a true two-dimensional array geometry can be approached. A wide number of applications for such a device exist in various disciplines. Oxidized porous silicon vacuum diodes were first developed in 1990. No systematic study had been done to characterize the performance of these devices as a function of the process parameters. We have done the first such study, fabricating diodes from p<100>, p<l I I>, and n<100> silicon substrates. Anodization current densities from llmAlcm2 to 15lmAlcm2 were used, and Fowler-Nordheim behavior was observed in over 80% of the samples. In order to effectively adapt this technology to mainstream vacuum microelectronic applications, a means of creating a gated triodic structure must be found. No previous attempts had successfully yielded such a device. We have succeeded in utilizing a novel metallization method to fabricate the first operational oxidized porous silicon vacuum microtriodes, and results are encouraging. Emission currents to 7OOpO were collected across-3mm of vacuum with an applied gate bias of less than 2OV. Simultaneous measurement of the gate current yielded current densities in excess of 70OAlcm2. Modulation of the emission current to 5MHz was observed.
Smith, Don Deewayne (1994). Development of an oxidized porous silicon vacuum microtriode. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -S6453.