The oxidized porous silicon vacuum microtriode: A revolutionary new type of field emission array

Yue began studying porous silicon-based vacuum microelectronic devices i n1990. Results from a device he dubbed the Oxidized Porous Silicon Field Emission Diode (OPSFED) showed that porous silicon (PS) offered an attractive alternative to standard field emission devices. Emission sites are reduced to near-atomic dimensions and site density is increased by six orders of magnitude. Yue, and later Madduri extracted electrons into the vacuum in a diode configuration, but no attempt to build a triode device had ever been successful. Using a novel metallization technique developed by Dr. R.C. Jaklevic et al. for use in STM imaging, the authors have successfully fabricated the first working PS-based vacuum microtriodes. Results are extremely encouraging. Collector currents up to 700 {micro}A were extracted across {approximately}3mm of vacuum with a pulsed DC gate bias of less than 20V. Simultaneous measurement of the gate current showed current densities to 700A/cm{sup 2}. Modulation of the emission to 5MH: was observed. Fowler-Nordheim plots show a slight curvature, as would be expected from extremely sharp emission tips, although it is stressed that the electroemissive mechanism is as yet unknown. Fowler-Nordheim plots for OPSFED`s made from the same material show an opposite curvature as predicted for emission from amore » large number of sites. Density of emitters approach a true two-dimensional limit, and many applications exist if the technology can be matured.« less