Improved Performance of Field Emission Vacuum Microelectronic Devices for Integrated Circuits
The movement from discrete transistors to integrated silicon circuits led to the rapid evolution of microscale electronics, but there has been no equivalent transition for the vacuum tube transistor. Difficulty integrating devices at microscales has hindered the use of vacuum electronic circuits, despite the unique advantages they offer in selected applications. The development of the field emission microfabricated cathode offers the potential to take advantage of the benefits of the vacuum technology in an integrated platform. This paper utilizes an MEMS carbon nanotube field emission vacuum microelectronic device as an active circuit element. Using a combination of particle trajectory simulation and experimental characterization, we investigated device performance in an integrated platform. Specifically, we present solutions for the operation of multiple devices in close proximity and for enhancing transmission (i.e., reducing grid loss) in vacuum field emission devices. The isolation structures reduced the crosstalk between neighboring devices from 14% on average, to nearly zero. Innovative geometries and a new operational mode reduced the grid loss by nearly three times, improving transmission of the current from the cathode to the anode from 25% from the previous designs to 70% on average. These performance enhancements are the important enablers for larger scale integration and for the realization of complex vacuum microelectronic circuits.