Effect of Nd3+ incorporation on the microstructure and chemical structure of RF sputtered ZnO thin films

The present work aims at investigating the effects that different levels of Nd atoms incorporation can have on the microstructure and chemical structure of ZnO thin films. Undoped and Nd-doped ZnO films were deposited by RF co-sputtering from pure ZnO and metallic Nd targets in Ar plasma onto Si, quartz and glass substrates. The Nd concentration in the ZnO host matrix was varied in the range 0-26 at. % by varying the bias applied to the Nd target. A comprehensive characterization of the films properties was performed by X-ray Photoelectron and Auger Electron spectroscopies, X-ray Fluorescence analysis, X-ray diffraction and Scanning Electron microscopy. At low Nd atomic concentration (Nd/Zn<0,07) Nd atoms were successfully incorporated into the ZnO matrix, whose crystalline structure was preserved. A deterioration of the ZnO würtzite phase was observed on the contrary with increasing Nd content in the films together with the precipitation of a second phase, identified as Nd2O3.