Electron emission mechanism from negative electron affinity surface and production of highly efficient electron emitter

1)研究了吸附在CVD金刚石表面的Cs的氧化过程。氧化过程与Si和GaAs相同。也就是说，随着氧的吸附，形成氧化物、过氧化物和超氧化物。超氧化物在氧气蒸发时是化学稳定的。2）硅和砷化镓的表面上有铯，很容易被氧化。相反，在表面上具有铯的金刚石不被氧化。3）结果，不形成干扰电子从表面发射的电势层。这使得能够在暴露于氧之后稳定地发射电子。这一事实对于实现实用的电子发射极是非常重要的。4）还研究了钡吸附金刚石表面。氧化过程类似于铯吸附的情况。吸附钡的金刚石表面也是潜在的电子发射体。5）脱附光谱研究发现，沉积在金刚石表面的钡层在400℃以下是热稳定的。6）测量了沉积铯金刚石表面的电子发射。电子发射阈值电场为0.8V/μm。当场强为15 V/μm时，发射电流密度为2 μA/mm^2。它对时间和暴露于空气相当稳定。确认了来自用于阳极的ITO的发光。

1) Oxidation process of Cs adsorbed on CVD diamond surfaces was investigated. The oxidation process is the same as that of Si and GaAs. Namely, with the adsorption of oxygen, oxide, peroxide and superoxide were formed. Superoxide is chemically stable upon oxygen exposure.2) Silicon and gallium arsenide with cesium on their surface is oxidized very easily. On the contrary diamond with cesium on the surface is not oxidized.3) As the result, the potential layer to disturb electron emission from the surface is not formed. This enables the stable electron emission after oxygen exposure. This fact is very important to realize practical electron emitters.4) Barium adsorbed diamond surface was also studied. The oxidation process is similar to the case of cesium adsorption. Barium adsorbed diamond surface is also potential for electron emitters.5) It was found from desorption spectrum study that barium layer deposited on diamond is thermostable up to 400℃.6) Electron emission from Cs deposited diamond surface was measured. Threshold field for electron emission was 0.8 V/μm. Emission current density of 2 μA/mm^2 was obtained for the field strength of 15 V/μm. It was fairly stable to time and exposure to air. Luminescence from ITO used for an anode was confirmed.