Stoichiometric Determination Of Thin Metal-Oxide Films

The stoichiometry of thin metal oxide films was investigated by using PIXE with an ultrathin window X-ray detector, and proton elastic scattering. As an example, measurements of the O/Zr concentration ratio for electron beam evaporated ZrO2-x films deposited on Al substrates are reported. The relative detection system efficiency for oxygen K X-rays to zirconium L X-rays has been determined experimentally by normalization to proton elastic scattering. The oxygen peak in the backscattered spectrum is resolved from the aluminum substrate peak for the proton energy of 4.6 MeV. In this energy region the oxygen cross section for elastic scattering has a broad resonance behaviour, and varies rather smoothly inside the energy interval of 20 keV, corresponding to the energy loss inside thin film (thickness approximately 400 nm). For PIXE measurements 2.6 MeV protons have been used.