Ultrathin metal films and particles on oxide surfaces: structural, electronic and chemisorptive properties

Surface studies of supported model catalysts

Journal of Physics Condensed Matter: Preface

One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near-edge region can be fitted to a simple expression in which the intercept gives the band-gap and the fitting exponent identifies the electronic transition as direct or indirect (see Tauc et al., Phys. Status Solidi 15, 627 (1966); these are often called “Tauc” plots). While the technique is powerful and simple, the accuracy of the fitted band-gap result is seldom stated or known. We tackle this question by refitting a large number of Tauc plots from the literature and look for trends. Nominally pure zinc oxide (ZnO) was chosen as a material with limited intrinsic deviation from stoichiometry and which has been widely studied. Our examination of the band gap values and their distribution leads to a discussion of some experimental factors that can bias the data and lead to either smaller or larger apparent values than would be expected. Finally, an easily evaluated figure-of-merit is defined that may help guide more accurate Tauc fitting. For samples with relatively sharper Tauc plot shapes, the population yields Eg(ZnO) as 3.276 ± 0.033 eV, in good agreement with data for single crystalline material.

Evaluation of the Tauc method for optical absorption edge determination: ZnO thin films as a model system

Interaction of nanostructured metal overlayers with oxide surfaces

Carbon doped ZnO: Synthesis, characterization and interpretation

Initial stages of InAs epitaxy on vicinal GaAs(001)-(2×4)

Island scaling in strained heteroepitaxy: InAs/GaAs(001).

Gold-silicon core-shell nanoparticles embedded in silica matrix, evident by transmission electron microscopy and x-ray photoelectron spectroscopy were synthesized by atom beam cosputtering followed by thermal annealing. Optical absorption studies revealed localized surface plasmon resonance (LSPR), which showed regular redshift from 500to583nm with increase in annealing temperature. The observed redshifts in the LSPR peaks are in close agreement with the theoretical calculations assuming Si nanoshells surrounding Au nanoparticles. The Au–Si core-shell formation is explained by Au–Si liquid nanodroplet formation at temperatures higher than the eutectic temperature, followed by phase separation during subsequent cooling.

Synthesis of gold-silicon core-shell nanoparticles with tunable localized surface plasmon resonance

Formation of coherently strained self-assembled InP quantum islands on InGaP/GaAs(001)

Shikha Varma

Papers

Carbon doped ZnO: Synthesis, characterization and interpretation

Initial stages of InAs epitaxy on vicinal GaAs(001)-(2×4)

Island scaling in strained heteroepitaxy: InAs/GaAs(001).

Synthesis of gold-silicon core-shell nanoparticles with tunable localized surface plasmon resonance

Formation of coherently strained self-assembled InP quantum islands on InGaP/GaAs(001)