AVS 60th International Symposium and Exhibition
    Synchrotron Analysis Focus Topic Tuesday Sessions
       Session SA+AS+MG+SS-TuA

Paper SA+AS+MG+SS-TuA4
Effective Attenuation Length for Titanium Nitride, Hafnium Oxide, Silicon, Silicon Dioxide, Lanthanum Lutetium Oxide, Lanthanum Calcium Manganite, and Gold from 1 keV up to 15 keV

Tuesday, October 29, 2013, 3:00 pm, Room 203 C

Session: HAXPES Studies on Interfaces and Buried Layers
Presenter: G.R. Castro, SpLine Spanisch CRG beamline at the European Synchrotron Radiation Facility, France
Authors: J. Rubio-Zuazo, SpLine Spanisch CRG beamline at the European Synchrotron Radiation Facility, France
G.R. Castro, SpLine Spanisch CRG beamline at the European Synchrotron Radiation Facility, France
Correspondent: Click to Email
Material composites, which combine different materials mostly multilayer hetero-structure, with specific and defined properties, are a promising way to create products with specific properties. In these materials the interfaces define many of their properties. The surfaces and interfaces play a fundamental role, and are the source of a great variety of new, and even unexpected, physical phenomena due to the existence of step changes in the structure and the electronic coordination. Third generation synchrotron radiation sources enables the extension of photoemission spectroscopy to higher electron kinetic energies (HAXPES, Hard X-ray PhotoElectron Spectroscopy) compensating the decrease of the photoionization cross-section for excitation energies in the hard X-ray region. HAXPES allows the accessibility to buried interfaces and bulk materials due to the dramatic increase of the effective attenuation length (EAL). Electronic, compositional and chemical depth profiles can be then performed in a non-destructive way over the tens-of nanometers scale with nanometer depth resolution. Such an important application of HAXPES is crucial for many condensed matter experiments and requires reliable EALs for high kinetic energy. EALs are well established for electrons with kinetic energies up to 2 keV. Even if EALs can be obtained by extrapolating well-known formulae, there is a lack of experimental data in the energy range between 1 and 15 keV. In the present study we have determined the EAL dependency on kinetic energy for titanium nitride (TiN), hafnium oxide (HfO2), silicon (Si), silicon dioxide (SiO2), lanthanum lutetium oxide (LaLuO3), lanthanum calcium manganite (La0.66Ca0.33MnO3), and gold (Au) from 1 keV up to 15 keV. A correlation between the EAL energy dependence and the material density is established. The EALs has been obtained by following either core level peak intensity dependence for a fixed kinetic energy as a function of the overlayer thickness or the core level peak intensity dependence with the photoelectron kinetic energy (i.e. photon energy) for a fixed overlayer thickness. The experimental set-up used is devoted to the combination of X-ray Diffraction (XRD) and HAXPES. Hence, we are able to determine the exact thickness and roughness of the layer from a fit of the X-ray reflectivity (Kiessig fringes) and simultaneously to obtain the EALs from the HAXPES signal evolution. It is important to stress that due to the simultaneous detection of the diffracted and photoemitted signal, the EALs, thickness and roughness determination correspond exactly to the same sample region.