Thin Films and Surfaces

Thin films and surface science were the fields of scientific interest in the four periods of the scientific life of Ernst Bauer: Munich (Germany), China Lake (California), Clausthal (Germany) and Tempe (Arizona). His achievements in these fields were honored in 1992 by the Medard Welch Award of the American Vacuum Society:  "for his contributions to the fundamental understanding of thin film nucleation and growth and for his invention, development and use of multiple surface characterization techniques to study those thin films."

Ernst Bauer started his scientific career in Munich with the study of the growth and structure of antireflection layers with electron microscopy and electron diffraction. His Ph.D. thesis was concerned with the structure and growth of thin evaporated layers of ionic materials and was the first extensive study of epitaxial and fiber orientation growth combining electron microscopy and electron diffraction. This experimental work stimulated a basic contribution to the theory of epitaxy. He derived in 1958 a classification of the basic thin film growth modes, which he called Volmer-Weber, Stranski-Krastanov and Frank-van der Merwe mechanisms. His thermodynamic criterion and terminology are used worldwide today. In the same year Ernst Bauer's book on "Electron diffraction: theory, practice and application" appeared.

Soon after his arrival in the Michelson Laboratory in China Lake surface science was born and he was involved early in it in order to understand thin film phenomena. In this period he started in situ thin film growth studies by conventional electron microscopy, UHV reflection electron diffraction, LEED and Auger electron spectroscopy. The difficulties encountered in the interpretation of the low energy electron diffraction (LEED) patterns reported by L. Germer in 1960 stimulated the invention in 1962 of the low-energy electron microscope (LEEM), which uses diffracted electrons for imaging. He was one of the first to recognize the importance of exchange, polarization, multiple scattering, and of the energy dependence of inelastic scattering of very slow electrons in LEED studies of surface, and he took them into account theoretically. The importance of adsorption on the initial growth of thin films led him also to adsorption studies. In these early years of UHV technique and surface science much of the work went into technological and methodological development.   

Thanks to excellent co-workers and strong financial support in his third scientific period in Technical University Clausthal Ernst Bauer could build up a broadly based surface science group encompassing a large variety of electron and ion beam techniques as well as optical methods.  The quantitative interpretation of thermal desorption spectra was developed with the goal to obtain information on the interactions in adsorption layers. Work function measurements were developed and used for the determination of the thermodynamic properties of two-dimensional systems with attractive lateral interactions. For the study of two-dimensional systems with repulsive or oscillatory interactions, his group developed LEED-diffractometry that allows the determination of critical exponents in chemisorbed layers with an accuracy comparable to that achieved with x-rays in physisorbed layers. He developed electron stimulated desorption (ESD) and static SIMS for the study of adsorbed layers and ultrathin films on single crystal surfaces; alkali ion scattering (ISS) for structural analysis of surfaces; field ion microscopy (FIM) of single atoms and clusters; UHV-SEM studies of surface melting. 

On the theoretical side his main interests were in the interactions of slow electrons with surfaces (J. Vac. Sci. Technol. 7 (1970) 3-12) and in two-dimensional phase transitions (Structure and Dynamics of Surfaces, Springer, Berlin 1987, p.115-179).

In the fourth period at the Arizona State University his efforts concentrate on the further development of laterally resolved surface science methods and on their application to the study of the growth, structure and properties of thin films, in particular of magnetic structure of ferromagnetic films and also oxide surfaces for heterogenious catalysis. 

 

References: (R) review or book chapter

E. Bauer: Phaenomenologische Theorie der Kristallabscheidung an Oberflaechen. I. Z. Kristallogr. 110 (1958) 372-394.

doi:10.1524/zkri.1958.110.1-6.372

E. Bauer: Epitaxy of metals on metals, Appl. Surf. Sci. 11/12 (1982) 479-494.

E. Bauer and H. Poppa: Recent Advances in Epitaxy, Thin Solid Films 12 (1972) 167-185. (R) 

E. Bauer: Chemisorbed Phases , in: Phase Transitions in Surface Films, eds.J.G. Dash and J. Ruvalds (Plenum Press, New York 1980) p.267-315. (R) 

E. Bauer: Metals on Metals, in: Chemical Physics of Solid Surfaces and Heterogeneous Catalysis, eds. D.A. King and D.P. Woodruff, Vol. III B (Elsevier, Amsterdam 1984) p.1-57 (R) 

J. Kolaczkiewicz and E. Bauer: Temperature dependence of the work function of adsorbate-covered metal surfaces: a new method for the study of two-dimensional phase transitions, Phys. Rev. Lett. 53 (1984) 485-488. (R) 

J. Kolaczkiewicz and E. Bauer: Experimental evidence for surface roughening in two dimensions, Phys. Rev. Lett. 54 (1985) 574-576. (R) 

E. Bauer and J.H. van der Merwe: Structure and growth of crystalline superlattices: from monolayer to superlattice Phys. Rev. B 33 (1986) 3657-3671. doi:10.1103/PhysRevB.33.3657

E. Bauer: Phase transitions on single crystal surfaces and in chemisorbed layers in: Structure and Dynamics of Surfaces (Topics in Current Physics 43) eds. W. Schommers and P. von Blanckenhagen (Springer, Berlin 1987) p.115-179. (R)

M. Jalochowski and E. Bauer: Quantum size and surface effects in the electrical resistivity and high-energy electron reflectivity of ultrathin lead films Phys. Rev. B 38 (1988) 5272-5280.

E. Bauer: Ultrathin metal films: from one to three dimensions, Ber. Bunsenges. Phys. Chem. 95 (1991) 1315-1325.(R)

M. Jalochowski, H. Knoppe, G. Lilienkamp and E. Bauer: Photoemission from ultrathin metallic films: quantum size effect, electron scattering and film structure, Phys. Rev. B 46 (1992) 4693-4701.

A. Pavlovska, D. Dobrev and E. Bauer: Orientation dependence of quasi-liquid layer formation an Sn and In crystals, Surf. Sci. 314 (1994) 341-352. N. Georgiev, A. Pavlovska and E. Bauer: Reconstruction and Deconstruction of a sp-Metal Surface, Phys. Rev. Lett. 75 (1995) 481-484.

E. Bauer: The Many Facets of Metal Epitaxy, in: The Chemical Physics of Solid Surfaces, eds. D.A. King and D.P. Woodruff (Elsevier, Amsterdam 1997) Vol. 8, p. 46-65.(R)

T. Duden and E. Bauer: Biquadratic exchange in ferromagnetic/ nonferromagnetic sandwiches: A spin-polarized low energy electron microscopy study, Phys. Rev. B59 (1999) 474-479.

E. Bauer: Growth of Thin Films, J. Phys.: Condensed  Matter 11(1999) 9365-9385.(R)      

R. Zdyb and E. Bauer: Spin-resolved unoccupied electronic band structure from quantum size oscillations in the reflectivity of slow electrons from ultrathin ferromagnetic crystals, Phys. Rev. Lett. 88 (2002) 166403-1-4.

A. Pavlovska, E. Bauer and D.J. Smith: In situ studies of the role of excess Ga on the growth morphology of thin GaN layers, Surf. Sci. 496 (2002) 160-178.

M.C.Tringides, M.Jalochowski and E. Bauer: Quantum size effects in metallic nanostructures, Physics Today 60 (2007) pp 50-54 (R).

R. Zdyb, E. Bauer: Coexistence of ferromagnetism and paramagnetism in a
ferromagnetic monolayer
, Phys. Rev. Lett. 100, 155704 (2008).

T.O. Mentes, A. Locatelli, L. Aballe, E. Bauer: Stress induced stripe formation in Pd/W(110), Phys. Rev. Lett. 101, 085701 (2008).

T.O. Mentes, N. Stojic, A. Locatelli, L. Aballe, N. Binggeli, M. A. Niño, M. Kiskinova and E. Bauer: Stress engineering at the nanometer scale: Two-component adlayer stripes, EPL, 94 (2011) 38003, p1-p6.

Q. Wu, R. Zdyb, E. Bauer, M.S. Altman: Growth, magnetism and ferromagnetic
thickness gap in Fe films on the W(111) surface
, Phys. Rev. B 87 (2013) 104410.

M. Suzuki, K. Kudo, K. Kojima, T. Yasue, N. Akutsu, W.A. Diño, H. Kasai, E. Bauer, T. Koshikawa: Magnetic domain patterns on strong perpendicular magnetization of Co/Ni multilayers as spintronics materials I: Dynamic observations, J. Phys.: Condens. Matt. 25 (2013) (406001) 8 pages.

 

              

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