Fabrication of high temperature processable CNT array for X-ray generation by micromachining

We report on the fabrication, characterization, and field emission behavior of cold electron cathodes that are specifically designed to be used for X-ray sources. The emitter was designed as a two-tier system, with the patterned CNT field emission array and the Pt comb electrode beneath. The micromachining patterning process, which enhanced the edge effect, significantly improved the field emission performance. By using an inorganic binder, the cathode could resist high temperature annealing up to 800°C. Our novel emitter showed relatively good field emission properties such as low turn on field, high current density, and good stability. We ascribed the improved emission properties after the annealing process to the oxygen desorption induced decrease of work function, and defect annealing which could stabilize the emitter. To check the application of the emitter, the fabricated emitter was sealed in a conventional X-ray tube. The blackened shade on the sensitive film confirmed the X-ray generation, which demonstrated that our emitter successfully survived the high temperature processing steps of the X-ray source fabrication.