Browsing by Subject "Surface photovoltage"

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    Chemically specific dynamic characterization of photovoltaic and photoconductivity effects of surface nanostructures
    (American Chemical Society, 2010) Ekiz, O. Ö.; Mizrak, K.; Dâna, A.
    We report characterization of photovoltaic and photoconductivity effects on nanostructured surfaces through light induced changes in the X-ray photoelectron spectra (XPS). The technique combines the chemical specificity of XPS and the power of surface photovoltage spectroscopy (SPV), with the addition of the ability to characterize photoconductivity under both static and dynamic optical excitation. A theoretical model that quantitatively describes the features of the observed spectra is presented. We demonstrate the applicability of the model on a multitude of sample systems, including homo- and heterojunction solar cells, CdS nanoparticles on metallic or semiconducting substrates, and carbon nanotube films on silicon substrates.
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    ItemOpen Access
    Probing dynamics of surface structures using x-ray photoelectron spectroscopy
    (Simplex Academic, 2012) Sezen, H.; Süzer, Şefik
    By incorporating laser illumination, and/or by application of electrical square-wave pulses to the sample, X-ray photoelectron spectroscopy is utilized to probe the dynamics of the surface structures in the range of 10-3 to 105 Hz. Different experimental methodologies are introduced, and their applications to investigate certain dynamical properties of two compound semiconductors, CdS and GaN are given. It is shown that dynamics of charging/discharging and surface photovoltage formation and its dissipation, and entanglement of various processes can be investigated by following the voltage shifts recorded in a chemical specific fashion.