Cr_2O_3涂层对Al_2O_3绝缘瓷二次电子发射特性的影响

Secondary Electron Emission Characteristic of Insulated Al_2O_3 Ceramics with Cr_2O_3 Coating

用Ｃｒ２Ｏ３涂复ａ－Ａｌ２Ｏ３绝缘瓷表面，并经热退火处理．观测了它们的二次电子发射系数、ＳＥＭ、ＸＲＤ、ＸＰＳ和ＥＥＬＳ．发现样品在退火后，涂层元素扩散进了Ａｌ２Ｏ３陶瓷基底，生成了新相；根据ＸＰＳ和ＥＥＬＳ的分析结果，表面层能隙减小，能隙中的缺陷态、杂质态及表面态增加，提供了更多可能的复合中心和陷阱中心，有利于非平衡载流子的散射跃迁，从而大大耗散能量，减少二次电子发射．

Cr2O3 coatings were applied to α-Al2O3 insulators and followed by heat treatment in special conditions. Secondary electron emission coefficient, SEM, XRD, XPS and EELS of the samples were measured and observed. During heat treatment, new phases can be formed, because the coatings can penetrate the surfaces of the insulators and mix with α-Al2O3. The experimental results of XPS and EELS show that due to the energy gaps of the surfaces decreasing, the densities of defect state, impurity state and surface state in the energy gaps increasing, more recombination centers and trapping centers can be formed, and that is favorable for the transition of non-equilibrium carriers and leading the decrease of secondaty electron emission.