@article{lucovsky_rayner_zhang_appel_whitten_2003, title={Band offset energies in zirconium silicate Si alloys}, volume={216}, ISSN={["0169-4332"]}, DOI={10.1016/S0169-4332(03)00429-X}, abstractNote={Transition metal silicates, (ZrO2)x(SiO2)1−x, with dielectric constants, k>10 have been proposed as alternative dielectrics for advanced Si devices. Studies by X-ray absorption, X-ray photoelectron and Auger electron spectroscopy are combined to identify the compositional variation of the valence and conduction band offset energies with respect to Si in Zr silicate alloys. The minimum conduction band offset energy, associated with localized Zr 4d∗-states, is ∼1.4 eV, and is independent of alloy composition, while valence band offsets decrease monotonically with increasing ZrO2 content. Differences between the coupling of tunneling electrons to localized Zr 4d∗ and extended Si 3s∗ states, characterized by respective tunneling masses of ∼0.5mo and ∼0.2mo, combine to contribute to a minimum in the direct tunneling current in the mid-silicate-alloy composition range, x∼0.4–0.6.}, number={1-4}, journal={APPLIED SURFACE SCIENCE}, author={Lucovsky, G and Rayner, B and Zhang, Y and Appel, G and Whitten, J}, year={2003}, month={Jun}, pages={215–222} }
 @article{lucovsky_raynor_zhang_fulton_nemanich_appel_ade_whitten_2003, title={Electronic structure of transition metal high-k dielectrics: interfacial band offset energies for microelectronic devices}, volume={212}, ISSN={["0169-4332"]}, DOI={10.1016/S0169-4332(03)00055-2}, abstractNote={Transition metal silicates, (ZrO2)x(SiO2)1� x, have dielectric constants k > 10 that make them attractive for advanced Si devices. Band offset energies relative to Si are an important factor in determining tunneling leakage current, and internal photoemission. Studies by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and X-ray absorption spectroscopy (XAS) are combined with ab initio calculations to identify the compositional variation of the band-gap, and valence and conduction band offset energies of Zr silicate alloys with respect to Si. The minimum conduction band offset, due to}, number={2003 May 15}, journal={APPLIED SURFACE SCIENCE}, author={Lucovsky, G and Raynor, GB and Zhang, Y and Fulton, CC and Nemanich, RJ and Appel, G and Ade, H and Whitten, JL}, year={2003}, month={May}, pages={563–569} }
 @article{appel_ade_guerek_stadler_mikalo_schmeisser_2003, title={Orientation studies of Si-phthalocyanine sulfonic acids cast on SiOx substrates}, volume={76}, ISSN={["1432-0630"]}, DOI={10.1007/s003390201320}, number={2}, journal={APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING}, author={Appel, G and Ade, H and Guerek, AG and Stadler, S and Mikalo, RP and Schmeisser, D}, year={2003}, month={Feb}, pages={177–182} }
 @article{harris_appel_ade_2003, title={Surface morphology of annealed polystyrene and poly(methyl methacrylate) thin film blends and bilayers}, volume={36}, ISSN={["0024-9297"]}, DOI={10.1021/ma0257043}, abstractNote={Thin films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) were spun-cast onto silicon substrates, annealed, and analyzed by atomic force microscopy (AFM), total electron yield (TEY), and partial electron yield (PEY) near-edge X-ray absorption fine structure (NEXAFS) spectroscopy in order to resolve conflicting prior literature regarding the tendency of PS to form a wetting layer or overlayer on top of PMMA. From the comparison of the three methods of analysis and on the basis of the extraordinary surface sensitivity of PEY NEXAFS, we conclude that PS does not form an overlayer in samples with morphologies near thermodynamic equilibrium. The PS forms droplets of a large size range on top of a PMMA layer that wets the hydrophilic SiOx substrate. From our results, the maximum thickness of a continuous PS wetting layer would be about 0.25 nm. This is in contrast to recent experiments that imply an equivalent PS wetting layer of about 5−10 nm is forming during annealing.}, number={9}, journal={MACROMOLECULES}, author={Harris, M and Appel, G and Ade, H}, year={2003}, month={May}, pages={3307–3314} }
 @article{lucovsky_zhang_rayner_appel_ade_whitten_2002, title={Electronic structure of high-k transition metal oxides and their silicate and aluminate alloys}, volume={20}, number={4}, journal={Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures}, author={Lucovsky, G. and Zhang, Y. and Rayner, G. B. and Appel, G. and Ade, H. and Whitten, J. L.}, year={2002}, pages={1739–1747} }
 @article{rightor_urquhart_hitchcock_ade_smith_mitchell_priester_aneja_appel_wilkes_et al._2002, title={Identification and quantitation of urea precipitates in flexible polyurethane foam formulations by X-ray spectromicroscopy}, volume={35}, ISSN={["1520-5835"]}, DOI={10.1021/ma0122627}, abstractNote={Scanning transmission X-ray microscopy (STXM) and atomic force microscopy have been used to study the morphology and chemical composition of macrophase-segregated block copolymers in plaque formulations based on water-blown flexible polyurethane foams. Although there has been a large body of indirect evidence indicating that the observed macrophase-segregated features in water-rich polyurethane foams are due principally to urea components, this work provides the first direct, spatially resolved spectroscopic proof to support this hypothesis. The STXM results are consistent with a segregation model where urea segments segregate, forming enriched phases with the majority of the polyether- polyol and urethane groups at the chain ends of the urea hard segments. Chemical mapping of the urea, urethane, and polyether distribution about the urea-rich segregated phases showed that the urea concentration changes gradually (across several hundred nanometers) in a butylene oxide-based foam. This mapping also showed the urea-rich segregated phases present as a partial network in an ethylene oxide/propylene oxide sample.}, number={15}, journal={MACROMOLECULES}, author={Rightor, EG and Urquhart, SG and Hitchcock, AP and Ade, H and Smith, AP and Mitchell, GE and Priester, RD and Aneja, A and Appel, G and Wilkes, G and et al.}, year={2002}, month={Jul}, pages={5873–5882} }
 @article{mikalo_appel_schmeisser_2001, title={Conductivity of silver exposed polypyrrole films.}, volume={122}, DOI={10.1016/S0379-6779(00)01338-2}, abstractNote={Electrochemically prepared conducting polypyrrole tosylate films were exposed to silver in a wide range of concentrations. Four-probe measurements of the dc conductivity of these films as well as two-probe ac conductivity measurements were performed. Small silver exposures lead to a dramatic change in the surface potentials and electronic structure, whereas the ac- and dc-conductivities appear not to be influenced. In the range of high silver exposures metallic conductivities due to the formation of a massive silver overlayer on top of the polypyrrole films are observed.}, number={1}, journal={Synthetic Metals}, author={Mikalo, R. P. and Appel, G. and Schmeisser, D.}, year={2001}, pages={91–93} }
 @article{lucovsky_rayner_kang_appel_johnson_zhang_sayers_ade_whitten_2001, title={Electronic structure of noncrystalline transition metal silicate and aluminate alloys}, volume={79}, ISSN={["0003-6951"]}, DOI={10.1063/1.1404997}, abstractNote={A localized molecular orbital description (LMO) for the electronic states of transition metal (TM) noncrystalline silicate and aluminate alloys establishes that the lowest conduction band states are derived from d states of TM atoms. The relative energies of these states are in agreement with the LMO approach, and have been measured by x-ray absorption spectroscopy for ZrO2–SiO2 alloys, and deduced from an interpretation of capacitance–voltage and current–voltage data for capacitors with Al2O3–Ta2O5 alloy dielectrics. The LMO model yields a scaling relationship for band offset energies providing a guideline for selection of gate dielectrics for advanced Si devices.}, number={12}, journal={APPLIED PHYSICS LETTERS}, author={Lucovsky, G and Rayner, GB and Kang, D and Appel, G and Johnson, RS and Zhang, Y and Sayers, DE and Ade, H and Whitten, JL}, year={2001}, month={Sep}, pages={1775–1777} }
 @article{gurek_appel_mikalo_schmeisser_2001, title={Synthesis of dihydroxy silicon phthalocyanine tetrasulfonic acid and poly-mu-oxo silicon phthalocyanine tetrasulfonic acid}, volume={5}, ISSN={["1088-4246"]}, DOI={10.1002/jpp.390}, abstractNote={ We describe the synthesis of tetrasulfonated silicon phthalocyanine and its oligomer product prepared by metal salt catalyzed polycondensation. The catalytic effect of H 2 O -free CaCl 2 in quinoline is used for the polycondensation of dihydroxy silicon phthalocyanine to the cofacially arrayed oligomer. Spectroscopic characterization and photoelectron spectroscopy data of the prepared compounds are reported. We present the first results on polypyrrole films doped with these substances. }, number={10}, journal={JOURNAL OF PORPHYRINS AND PHTHALOCYANINES}, author={Gurek, AG and Appel, G and Mikalo, RP and Schmeisser, D}, year={2001}, month={Oct}, pages={751–757} }
 @article{morin_ikeura-sekiguchi_tyliszczak_cornelius_brash_hitchcock_scholl_nolting_appel_winesett_et al._2001, title={X-ray spectromicroscopy of immiscible polymer blends: polystyrene-poly(methyl methacrylate)}, volume={121}, DOI={10.1016/S0368-2048(01)00335-8}, abstractNote={Abstract Spun cast thin films of blends of low and high molecular weight mono-disperse polystyrene (PS) and poly(methyl methacrylate) (PMMA) with nominal compositions ranging from 66/33 wt.%/wt.% (w/w) up to 10/90 w/w PS/PMMA have been studied, as-made and after annealing. Two synchrotron-based X-ray microscopies — scanning transmission X-ray microscopy (STXM) and X-ray photoemission electron microscopy (X-PEEM) — as well as several variants of atomic force microscopy (AFM) were used to probe the composition and morphology of the bulk and surface of these blends. The chemical sensitivities and spatial resolutions of these three techniques are compared. All samples are observed to have a PS signal in the C 1s X-ray absorption spectrum of the surface of the PMMA-rich domains as measured in the X-PEEM. A continuous thin PS layer is not expected at a PMMA surface since neither polymer should wet the other at thermodynamic equilibrium. The likely origin of this PS surface signal is from a bimodal distribution of PS domain sizes with the PS signal arising from domains at the surface which are smaller than the ∼200-nm resolution of the X-PEEM. High resolution AFM and STXM provide direct evidence for this explanation.}, number={1-3}, journal={Journal of Electron Spectroscopy and Related Phenomena}, author={Morin, C. and Ikeura-Sekiguchi, H. and Tyliszczak, T. and Cornelius, R. and Brash, J. L. and Hitchcock, A. P. and Scholl, A. and Nolting, F. and Appel, G. and Winesett, D. A. and et al.}, year={2001}, pages={203–224} }