Yevgen Syryanyy
supervisor: Iraida Demchenko
In recent years, the materials science has made increasing use of ion implantation as a method of doping semiconductors in order to obtain either novel material properties or improve the existing ones. However, the important limitation of ion implantation technology is the build-up of lattice disorder, which leads to deterioration of the physical characteristics of the studied materials. Consequently, the resulting defective structures caused by the ion implantation process and methods of their elimination (e.g., sample annealing) require systematic and profound study. This work is devoted to testing the possibility of donor-acceptor clustering in Yb-implanted ZnO using XANES as the main experimental method.
Polarization-dependent XANES spectra of w-ZnO thin films (primary and implanted Yb) were analyzed. Calculations of XANES spectra with orbital resolution provided by the FEFF code for the O K edge successfully reproduced the observed anisotropic effects, shedding light on the responsible mechanisms. A linear combination of theoretical models corresponding to selected point defects and their complexes confirmed the presence of donor-acceptor complexes in the examined samples. In addition, it was possible to estimate the numerical values of the concentrations of the selected point defects and their complexes formed in the examined samples.