Quantitative counting of Zn and O atoms by atomic resolution off-axis and in-line electron holography

Abstract

We present quantitative counting of Zn and O atoms in zinc oxide epitaxial thin film by different routes; reconstruction of phase from the side and central bands of atomic resolution off-axis and in-line electron holography. Results show that the reconstructed phase from both the side and the central bands and the corresponding number of Zn (Z = 30) and O (Z = 8) atoms are in close agreement with the systematic increase in the number of atoms for a sample area less than the extinction distance. However, complete disagreement is observed for the sample area more than the extinction distance. On the other hand, the reconstructed phase obtained via in-line holography shows no systematic change with thickness for the same sample. Phase detection limits and the atomic model used to count the atoms are discussed.