Hop Funnel Structure for LFEs
Faculty Mentor Information
Dr. Jim Browning, Boise State University
Presentation Date
7-15-2026
Abstract
The Boise State CMEMs (Ceramic Micro Electrical Mechanical Systems) Lab integrates field emitter arrays (FEAs) into vacuum electron devices. Accomplished through funnels called electron hop funnels, electrons are emitted from the FEA into the wide end of the funnel and "hop" up the sloped walls. The electrons exit the narrow end of the funnel as a dense, uniform electron beam. These electron sources have application in microwave vacuum electron devices and vacuum transistors. This poster demonstrates the fabrication process of a FEA jig and hop funnel structure, both constructed from the vacuum compatible material of low temperature co-fired ceramic (LTCC). This FEA jig houses the lateral field emitter wafer, with various jumped connections applied that are necessary to operate the device. The hop funnel structure is made by milling through a thin layer of LTCC, using an angled bit. Results of fabrication of the holes and funnels were measured at an exit size of 250 microns and an entry size of 2300 microns. When fired these funnels had mild bumps of 1-3 microns in size. This funnel can be placed over the FEA jig on an emitter to test the device for functionality.
Hop Funnel Structure for LFEs
The Boise State CMEMs (Ceramic Micro Electrical Mechanical Systems) Lab integrates field emitter arrays (FEAs) into vacuum electron devices. Accomplished through funnels called electron hop funnels, electrons are emitted from the FEA into the wide end of the funnel and "hop" up the sloped walls. The electrons exit the narrow end of the funnel as a dense, uniform electron beam. These electron sources have application in microwave vacuum electron devices and vacuum transistors. This poster demonstrates the fabrication process of a FEA jig and hop funnel structure, both constructed from the vacuum compatible material of low temperature co-fired ceramic (LTCC). This FEA jig houses the lateral field emitter wafer, with various jumped connections applied that are necessary to operate the device. The hop funnel structure is made by milling through a thin layer of LTCC, using an angled bit. Results of fabrication of the holes and funnels were measured at an exit size of 250 microns and an entry size of 2300 microns. When fired these funnels had mild bumps of 1-3 microns in size. This funnel can be placed over the FEA jig on an emitter to test the device for functionality.