XPS sputter depth profiling of the chemical states for SrTiO₃/Si interface by O₂⁺ ion beams

Abstract

Because the chemical states of the elements in SrTiO, thin film on Si are reduced by argon ion beam bombardment, it was impossible to sputter depth profile the chemical states of SrTiO, thin film by argon ion beams. In this paper, it is reported that the undistorted chemical states of Ti and Si a t the SrTiO,/Si interface can be determined with oxygen ion beams a t the appropriate 70' angle of incidence, with which either metallic Ti is not oxidized or Ti in SrTiO, is not reduced. Under the sputter depth profiling conditions, the chemical state of Ti a t the SrTiO,/Si interface could be successfully characterized and the effects of post-annealing at high temperature on the chemical state of Ti were studied. A significant number of Ti atoms in the metallic state were observed at the SrTiO,/Si interface without any post-annealing but all of them were oxidized to the Ti4+ chemical state after 2 h postannealing a t the temperatures above 600 OC under oxygen flow. The dielectric properties of SrTiO, thin films on Si were well correlated to the oxidation state of Ti and the broadening of the interface SiO, layer induced by postannealing a t high temperature.

Synthesis and transport properties of SrTiO3−xNy/SrTiO3−δlayered structures produced by microwave-induced plasma nitridation

“…The typical O and Sr spectra for all the samples shown in figure 5 did not exhibit significant changes during the depthprofile analysis. The O 1s peak obtained from the SrTiO 3−x N y surface layer was located at a binding energy of 531 eV, while the peak for Sr 3d was found at 134.4 eV, which is in agreement with peak positions reported for STO [26,29,31].…”

A novel synthetic approach for the preparation of sulfated titania with enhanced photocatalytic activity

“…The binding energy values for Ti 2p 1/2 and Ti 2p 3/2 for different oxidation states of titanium as reported were 454.1 and 460.2 eV for Ti 0 , 454.9 and 460.8 eV for Ti +2 , 456.9 and 462.6 eV for Ti +3 , and 458.9 and 464.6 eV for Ti in +4 state. 37 For pure titania the binding energy of Ti 2p 3/2 is 458.8 eV. The Ti 2p 3/2 binding energy of P1 was 459.1 eV, which is slightly higher than the normal Ti +4 binding energy and may be due to a stronger interaction between SO 4 22 and the Ti-cation with increased positive polarity on the titanium cation.…”

Oxidation of molybdenum surfaces by reactive oxygen plasma and O2+ bombardment: an auger and XPS study

“…However, in connection with such processes it is worth mentioning that while the papers dealing with the interaction of noble gas ions with oxide targets are very numerous,28h30 those reporting the interaction of reactive gases with metal or oxide targets are more scarce. 31,32 In the present paper we study by AES and XPS the di †erent oxidation processes occurring at room temperature on a polycrystalline Mo foil when it is subjected to the above-mentioned oxidation procedures. The results suggest that chemical and ballistic e †ects are involved in the processes.…”