Modeling and fabricating micro-cavity integrated vacuum tubes

The authors discuss the modeling and fabricating miniature, vacuum, field-emission diodes and triodes for use in electronics in hazardous environments. They are micrometer-sized devices that are fabricated on a semiconductor wafer using integrated-circuit fabrication techniques and that use field emission rather than thermionic emission to generate charge carriers. Compared to existing semiconductor devices, they should be faster and much more tolerant of high temperatures and radiation. The device design uses the sacrificial layer technique to produce the device on a silicon wafer. All of the processing is completely compatible with existing integrated-circuit technology, making possible eventual integration of these devices and existing integrated-circuit components. To model these devices, the authors have used a static field modeling code to analyze the effect of device design variations on the field at the field-emission tip. Using these field results, they have calculated the tube´s plate resistance, transconductance, gain, and current versus voltage characteristics. They have completed construction of a diode and are currently testing and interpreting the results. In addition, they have nearly completed a triode design.