纳米金属氧化物气敏薄膜的最佳晶粒尺寸和介观效应

纳米金属氧化物气敏薄膜存在灵敏度的最佳膜厚l*和最佳晶粒尺寸r0*,其值与材料和工艺有关.最佳晶粒尺寸的存在是一种新的介观效应,它来自晶粒尺寸缩小到一定程度时反映吸附氧负离子的Fermi统计失效;根据当晶粒尺寸缩小到特征长度rm时晶粒将保持电中性的Kubo理论对Fermi统计公式进行修正,从而给出了最佳晶粒尺寸r0*=2rm的结果,并用Kubo理论电子逸出功公式估算了rm与r0*的数值.

The Optimun Grain Size of Nano Metal Oxide Gas Sensing Thin - Film and Mesoscopic Effect

The optimum film thickness l* and optimum grain size r0* for sensitivity in nano metal oxide gas sensing thin film are existent, and the value is dependent on the material and technics. The existence of optimum grain size is a new kind of mesoscopic effect, which is from the disability of Fermi statistics for negative oxide ions when the grain size reduced to a certain extent, according to the modification of Kubo theory for the grains keeping neuter to fermi statistics when the grain size reduced to character length rm , we get that r0* =2rm, and the values of rm and optimum grain size r0* are estimated with the word function in Kubo theory.