摘要
Different atomic ratio La/O film cathodes were prepared by pulsed laser deposition under various vacuum conditions. The emission properties were measured and their surface composition was investigated with in situ AES analyses. The function of oxygen in thermoionic emission of Mo-La2O3 cathode was investigated. Excess oxygen is negative to electron emission because lanthanum is easy to become stable La2O3, but proper proportion oxygen can weaken the evaporation of lanthanum and conduce to cathodes＇ stable work. The formation of oxygen vacancies enhances semiconductor property of La-O compound and improves greatly the performance of cathodes.
Different atomic ratio La/O film cathodes were prepared by pulsed laser deposition under various vacuum conditions. The emission properties were measured and their surface composition was investigated with in situ AES analyses. The function of oxygen in thermoionic emission of Mo-La2O3 cathode was investigated. Excess oxygen is negative to electron emission because lanthanum is easy to become stable La2O3, but proper proportion oxygen can weaken the evaporation of lanthanum and conduce to cathodes＇ stable work. The formation of oxygen vacancies enhances semiconductor property of La-O compound and improves greatly the performance of cathodes.
