XPS and DFT study of pulsed Bi-implantation of bulk and thin-films of ZnO-The role of oxygen imperfections

Abstract

An atomic and electronic structure of the bulk and thin-film morphologies of ZnO were modified using pulsed Bi-ion implantation (1 x 10(17) cm(-7) fluence, 70 min exposure under Bi-ion beam, E-Bi(+) =30 keV, pulsed ion-current density of not more than 0.8 mA/cm(2) with a repetition rate of 12.5Hz). The final samples were qualified by X-ray photoelectron core-level and valence band mapping spectroscopy applying ASTM materials science standard. The spectroscopy data obtained was discussed on the basis of DFT-models for Bi-embedding into ZnO host-matrices. It was established that in the case of direct Bi-impurities insertion into the employed ZnO-host for both studied morphologies neither the only "pure" Bi2O3-like phase nor the only "pure" Bi-metal will be preferable to appear as a secondary phase. An unfavorability of the large cluster agglomeration of Bi-impurities in ZnO-hosts has been shown and an oxygen 2s electronic states pleomorphizm was surely established. (C) 2016 Elsevier B.V. All rights reserved.