On PbTiO3-(111)-Pt interfacial layers and their x-ray photoelectron spectroscopy signature

In this work emphasis is placed on the investigation of interfacial layers between sol-gel processed PbTiO3 (PTO) thin films and (111)Pt terminated silicon substrates. The methods used are x-ray diffraction, x-ray photoelectron spectroscopy (XPS) combined with depth profiling, and atomic force microscopy (AFM). In order to avoid artifacts related to ion bombardment, e.g., reduction of Pb ions and preferential sputtering, gentle argon ion bombardment conditions were first derived. AFM investigations of native and ion bombarded films at different stages of depth profiling show that the films are homogenously sputtered, whereby the film roughness remains practically unchanged in the course of sputtering. An annealing treatment at 550 °C under reducing atmosphere was used to provoke the formation of an interfacial intermetallic (111)PtxPb phase, which is shown to coexist with an amorphous oxide film. This could allow us to establish the XPS signature of the intermetallic phase. A negative shift of the Pt (4f)...