CBED and EELS Measurements of Post-Irradiated Aluminum Specimen Thickness

Abstract

CBED and EELS are most common methods to determine the thickness of the TEM specimen. In this work, specimen thickness of He-ion irradiated Al is measured respectively by CBED and EELS under 200kV. The helium concentration and the atomic displacement damage level are 2000appm and 0.2dpa, respectively. The CBED results show that the measurements of extinction distance match the calculations of effective extinction distance considering the deviation vector of the crystal. Moreover, it is proven by modeling analysis that He-ion irradiation does not affect the thickness measurements of extinction distance. Compared with CBED, the specimen thickness, measured by EELS, is larger, and may be attributed to the decrease of the zero-loss peak due to a part of elastic scattering electronsloss and the larger inelastic scattering mean free path selected. The EELS measurement error is less than 20%,consistent with the accuracy (about 20%) byK. Iakoubovskiiet al.