【摘要】 在扫描电镜(SEM)中,通过记录和实时处理电子束辐照样品过程中产生的吸收电流Ia,评价非导电样品的荷电效应。对于非导电样品,Ia的绝对值很小,且变化幅度很大,这是电荷在非导电样品表面被捕获、积累和释放过程的直接反映。此外,Ia还可用来评价荷电补偿(改变环境压力、改变成像参数及对样品表面进行导电处理)的效果。更多还原

【Abstract】 A measuring system of absorbe current I_a was established on a scanning electron microscope （SEM）. The charge amount on non-conductive samples under electron beam irradiation in SEM could be estimated by recording and in-situ processing the absorbe current intensity I_a. Compared with the conductive samples, the Ia values of the insulate samples were small and unstable. It was the direct reflection of the process when electrons were trapped, accumulated and detrapped on the surface of an insulate samples. Furthermore, the value of Ia was used to evaluate the effect of charging compensation methods, such as change of environmental pressure, imaging parameters and specimen electrically coating. With increasing the pressure of 1.0×10^-2 Pa to 2.0×10^-2Pa, the charging phenomenon on polycrystalline Al₂O₃ was reduced and the corresponding Ia values increased. The I_a fluctuation values indicated that the charging effects of Al₂O₃ haven’t been eliminated at the pressure of 2.0×10^-2 Pa. The Au-coated Al₂O₃-SiO₂ sample was charge-free, and its I_a value increased and became stable obviously.更多还原