Surface & Coatings Technology | 2019
Local structural changes induced by ion bombardment in magnetron sputtered ZnO: Al films: Raman, XPS, and XAS study
Abstract
Abstract Negative oxygen (O−) ions in the sputter deposition of oxides play a non-negligible role in determining their structures as well as physical properties. Knowledge of bombardment by O− ions induced local disorder in magnetron sputtered ZnO: Al (AZO) films is of fundamental interesting whereas that is currently limited. Here we report our initial results of the local structural changes characterized by a combination of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). The bombardment conditions during the film deposition was varied through changing the discharge voltage (i.e., |Vd|\u202f=\u202f80–220\u202fV) and the substrate positions (i.e., center or erosion region of the target). We found that highly-energetic O− ions bombardment induced a coexistence of various point defects such as oxygen vacancies (VO), oxygen interstitials (Oi), and zinc interstitials (Zni). The concentration of these defects and thus the local disorder can be noticeably reduced through decreasing the |Vd| down to a sufficient low level. These results can be used to further optimize the growth processes to achieve the ZnO-based and related thin films with a high structural order.