Charging behavior of Al2O3 and AlN under positive and negative charge injection using a kV electron beam

Under electron irradiation, insulating materials may charge either negatively or positively depending on their electron emission properties and characteristics of the incident electrons. The electrical behavior of these materials is linked to the sign of the injected charge. The aim here is to describe an electron beam based method that can be used to study the electrical behaviors of insulators under either positive or negative charge injection. The method was tested on ceramics samples, Al2O3 and AlN. It was shown that the electrical behaviors of both materials under e-irradiation are very different according the sign of the injected charge. Negative charging results to stable space charge for Al2O3 and on the contrary it leads to a fast charge-decay for AlN. Remarkably, reversed trends are observed for positive charge injection. The practical consequences of these results are then discussed.