Surface Characterizations and Selective Etching of Sr-Rich Segregation on Top of SrVO3 Thin-Films Grown by Pulsed Laser Deposition

摘要

Since SrVO3 (SVO) can be used as a highly conductive material for perovskite heterostructures, the control of surface morphology and chemistry of such thin-films are essential. Using pulsed laser deposition, two distinct topographies can be produced. Thus, by tuning oxygen pressure in the growth chamber during cooling, smooth or partially covered by self-oriented Sr3V2O8 nanorods surfaces can be grown. This study manages to correlate the two typical topographies, revealed by atomic force microscopy (AFM), with their chemical compositions obtained by X-ray photoelectron spectroscopy (XPS). At first, a model describes their initial surface chemistry through the Sr/V cationic ratio and the (Sr+V)/O-ox ratio. Furthermore, using sputter-depth profiling, post-thermal treatments and wet chemical etching, SVO thin-film chemical compositions are extensively studied. We demonstrate that they are composed of stoichiometric SVO phase covered by Sr-rich layer on top. Finally, treatment in water for 180 seconds helps to remove Sr-rich phases. Sr3V2O8 nanorods are found selectively dissolved leaving a surface nano-imprint. Moreover, on smooth SVO surfaces, a balanced Sr/V cationic ratio of 1.0 +/- 0.1 is obtained. These results appear very promising for SVO thin-films surface preparation and further development as electrodes for electronic devices.