Current–voltage characteristic of alumina and aluminum nitride with or without electron irradiation

The current–voltage (I–V) characteristics of single- and poly-crystal alumina and aluminum nitride (AlN) were measured at temperatures ranging from room temperature to 723 K with or without 1 MeV electron irradiation in a high voltage electron microscope (HVEM). Both alumina and AlN specimens exhibit non-ohmic I–V characteristics without irradiation. The I–V characteristics in alumina, however, change from non-ohmic to almost ohmic under electron irradiation. But the I–V characteristics in AlN is still non-ohmic under irradiation. There are remarkable differences in I–V characteristics between the alumina and AlN specimens. The non-ohmic behavior is due to the electronic barrier formed near the interface between the titanium electrode and the alumina or AlN specimen. No bulk and surface radiation induced electrical degradation (RIED) was found in AlN up to 1.5×10−5 dpa.