Fabrication and Emission Properties of Single Crystal Lanthanum Hexaboride Tip

Field emission cathode single tip was fabricated by electro-chemical etching method. The materials used here were single crystal lanthanum hexaboride (LaB6), polycrystalline lanthanum hexaboride, molybdenum, and tungsten, respectively. Electron emission characteristics of single crystal LaB6 cold cathode were studied in a diode test cell in vacuum system. When the distance between the single crystal LaB6 tip and the anode was 0.2mm, current density of 1.25times104 A/cm2 was obtained at a pressure of 3.4times10-4 Pa with DC-3000 V bias applied to the anode. Results show that single crystal LaB6 cold cathode, due to its high current density, low evaporation rates, high stability, strong ability of antipoisoning and long life, is an excellent electron source, particularly fitting for traveling-wave tubes, klystrons and other large vacuum apparatus