Ernst G. Bauer
Encyclopedia
Ernst G. Bauer is a German-American physicist. He is known for his studies in the field of surface science
. His most notable contributions are his work on establishing thin film
growth and nucleation mechanisms, and his invention of the low energy electron microscope. He is currently holding the position of Distinguished Research Professor
at the Arizona State University
.
, where he received his MS
(1953) and PhD
(1955) degrees in physics
. In 1958 he moved to the Michelson Laboratory in China Lake, California
, where he became the Head of the Crystal Physics Branch and a U.S. citizen. He assumed the position of Professor
and Director of the Physics Institute at the Technical University Clausthal, Germany
, in 1969. He was appointed Distinguished Research Professor in 1991 at the Arizona State University
. He continued his research activity in Germany until 1996. Since 1996 he is working full-time at the Arizona State University
.
and film growth since the mid-fifties. He started his scientific career in Munich
with the study of the growth and structure of antireflection layers with electron microscopy and electron diffraction
. His PhD
thesis was concerned with the structure and growth of thin evaporated layers of ionic materials and was the first systematic 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 Frank-van der Merwe (layer-by-layer growth), Volmer-Weber (island growth) and Stranski-Krastanov growth
(layer+island growth). 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.
, surface science
was born. 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
. 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 surfaces, 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. The invention in 1962 of the Low Energy Electron Microscope (LEEM) was stimulated by a scientific dispute with Lester Germer
about the difficulties in the interpretation of low energy electron diffraction
(LEED) patterns. Ernst Bauer realized that electron microscopy using the diffracted electrons for imaging would be extremely important for the future of the surface science
. He constructed the first LEEM prototype and reported it at the Fifth International Congress for Electron Microscopy in 1962.
At the Technical University Clausthal Ernst Bauer built 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 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. In this period (in 1985) the LEEM came also to fruition. In the late eighties/ nineties Ernst Bauer extended the LEEM technique in two directions by developing two new surface microscopy methods: Spin-Polarized Low Energy Electron Microscopy (SPLEEM) and Spectroscopic Photo Emission and Low Energy Electron Microscopy (SPELEEM).
Surface science
Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid-gas interfaces. It includes the fields of surface chemistry and surface physics. Some related...
. His most notable contributions are his work on establishing thin film
Thin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
growth and nucleation mechanisms, and his invention of the low energy electron microscope. He is currently holding the position of Distinguished Research Professor
Professor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...
at the Arizona State University
Arizona State University
Arizona State University is a public research university located in the Phoenix Metropolitan Area of the State of Arizona...
.
Biography
Ernst Bauer studied at the Munich University, GermanyGermany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, where he received his MS
Master's degree
A master's is an academic degree granted to individuals who have undergone study demonstrating a mastery or high-order overview of a specific field of study or area of professional practice...
(1953) and PhD
Doctor of Philosophy
Doctor of Philosophy, abbreviated as Ph.D., PhD, D.Phil., or DPhil , in English-speaking countries, is a postgraduate academic degree awarded by universities...
(1955) degrees in physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
. In 1958 he moved to the Michelson Laboratory in China Lake, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, where he became the Head of the Crystal Physics Branch and a U.S. citizen. He assumed the position of Professor
Professor
A professor is a scholarly teacher; the precise meaning of the term varies by country. Literally, professor derives from Latin as a "person who professes" being usually an expert in arts or sciences; a teacher of high rank...
and Director of the Physics Institute at the Technical University Clausthal, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, in 1969. He was appointed Distinguished Research Professor in 1991 at the Arizona State University
Arizona State University
Arizona State University is a public research university located in the Phoenix Metropolitan Area of the State of Arizona...
. He continued his research activity in Germany until 1996. Since 1996 he is working full-time at the Arizona State University
Arizona State University
Arizona State University is a public research university located in the Phoenix Metropolitan Area of the State of Arizona...
.
Thin Film Growth
Ernst Bauer has contributed to the field of epitaxyEpitaxy
Epitaxy refers to the deposition of a crystalline overlayer on a crystalline substrate, where the overlayer is in registry with the substrate. In other words, there must be one or more preferred orientations of the overlayer with respect to the substrate for this to be termed epitaxial growth. The...
and film growth since the mid-fifties. He started his scientific career in Munich
Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...
with the study of the growth and structure of antireflection layers with electron microscopy and electron diffraction
Electron diffraction
Electron diffraction refers to the wave nature of electrons. However, from a technical or practical point of view, it may be regarded as a technique used to study matter by firing electrons at a sample and observing the resulting interference pattern...
. His PhD
Doctor of Philosophy
Doctor of Philosophy, abbreviated as Ph.D., PhD, D.Phil., or DPhil , in English-speaking countries, is a postgraduate academic degree awarded by universities...
thesis was concerned with the structure and growth of thin evaporated layers of ionic materials and was the first systematic extensive study of epitaxial and fiber orientation growth combining electron microscopy and electron diffraction
Electron diffraction
Electron diffraction refers to the wave nature of electrons. However, from a technical or practical point of view, it may be regarded as a technique used to study matter by firing electrons at a sample and observing the resulting interference pattern...
. This experimental work stimulated a basic contribution to the theory of epitaxy
Epitaxy
Epitaxy refers to the deposition of a crystalline overlayer on a crystalline substrate, where the overlayer is in registry with the substrate. In other words, there must be one or more preferred orientations of the overlayer with respect to the substrate for this to be termed epitaxial growth. The...
. He derived in 1958 a classification of the basic thin film
Thin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
growth modes, which he called Frank-van der Merwe (layer-by-layer growth), Volmer-Weber (island growth) and Stranski-Krastanov growth
Stranski-Krastanov growth
Stranski–Krastanov growth is one of the three primary modes by which thin films grow epitaxially at a crystal surface or interface...
(layer+island growth). 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.
Surface Science and LEEM
Soon after his arrival at the Michelson Laboratory in CaliforniaCalifornia
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, surface science
Surface science
Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid-gas interfaces. It includes the fields of surface chemistry and surface physics. Some related...
was born. He was involved early in it in order to understand thin film
Thin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
phenomena. In this period he started in situ thin film
Thin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
growth studies by conventional electron microscopy, UHV
UHV
UHV may refer to:* University of Houston–Victoria* Ultra high vacuum* Ultra high voltage power line...
reflection electron diffraction, LEED and Auger electron spectroscopy
Auger electron spectroscopy
Auger electron spectroscopy is a common analytical technique used specifically in the study of surfaces and, more generally, in the area of materials science...
. 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 surfaces, 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
UHV
UHV may refer to:* University of Houston–Victoria* Ultra high vacuum* Ultra high voltage power line...
technique and surface science
Surface science
Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid-gas interfaces. It includes the fields of surface chemistry and surface physics. Some related...
much of the work went into technological and methodological development. The invention in 1962 of the Low Energy Electron Microscope (LEEM) was stimulated by a scientific dispute with Lester Germer
Lester Germer
Lester Halbert Germer was an American physicist. With Clinton Davisson, he proved the wave-particle duality of matter in the Davisson–Germer experiment, which was important to the development of the electron microscope. These studies supported the theoretical work of De Broglie. He also studied...
about the difficulties in the interpretation of low energy electron diffraction
Low energy electron diffraction
Low-energy electron diffraction is a technique for the determination of the surface structure of crystalline materials by bombardment with a collimated beam of low energy electrons and observation of diffracted electrons as spots on a fluorescent screen.LEED may be used in one of two ways:#...
(LEED) patterns. Ernst Bauer realized that electron microscopy using the diffracted electrons for imaging would be extremely important for the future of the surface science
Surface science
Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid-gas interfaces. It includes the fields of surface chemistry and surface physics. Some related...
. He constructed the first LEEM prototype and reported it at the Fifth International Congress for Electron Microscopy in 1962.
At the Technical University Clausthal Ernst Bauer built up a broadly based surface science
Surface science
Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid-gas interfaces. It includes the fields of surface chemistry and surface physics. Some related...
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
Work function
In solid-state physics, the work function is the minimum energy needed to remove an electron from a solid to a point immediately outside the solid surface...
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
Diffractometer
A diffractometer is a measuring instrument for analyzing the structure of a material from the scattering pattern produced when a beam of radiation or particles interacts with it....
that allows the determination of critical exponents in chemisorbed layers with 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
Single crystal
A single crystal or monocrystalline solid is a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries...
surfaces; alkali
Alkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
ion scattering (ISS) for structural analysis of surfaces; field ion microscopy (FIM) of single atoms and clusters; UHV
UHV
UHV may refer to:* University of Houston–Victoria* Ultra high vacuum* Ultra high voltage power line...
-SEM
Scanning electron microscope
A scanning electron microscope is a type of electron microscope that images a sample by scanning it with a high-energy beam of electrons in a raster scan pattern...
studies of surface melting. In this period (in 1985) the LEEM came also to fruition. In the late eighties/ nineties Ernst Bauer extended the LEEM technique in two directions by developing two new surface microscopy methods: Spin-Polarized Low Energy Electron Microscopy (SPLEEM) and Spectroscopic Photo Emission and Low Energy Electron Microscopy (SPELEEM).
Awards
- Gaede Prize of the German Vacuum Society (1988) - For the invention of the Low Energy Electron Microscope.
- Medard W. Welch AwardMedard W. Welch AwardThe award is given to scientists who demonstrated outstanding research in the fields pertinent to American Vacuum Society. It was established in 1969 in memory of Memory of Medard W. Welch, a founder of American Vacuum Society. The prestige of the award is created by its recipients and their...
of the American Vacuum Society (1992) - 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. - Niedersachsenpreis for Science (1994) - for the development of LEEM and for his thin film research.
- Award of the Japan Society for Promotion of Science’s 141st Committee on Microbeam Analysis (2003) - for outstanding research on microbeam analysis and contributions to the JSPS 141 Committee.
- BESSY Innovation Award on Synchrotron Radiation (2004) - Excellent contributions towards the development of the photoelectron emission microscope (PEEM) as energy, space and time resolved detection system of photoelectrons.
- Davisson-Germer Prize of the American Physical Society (2005) - for contributions to the science of thin-film nucleation and growth, and for the invention of Low Energy Electron Microscope.
- Humboldt Research PrizeThe Humboldt PrizeThe Humboldt Prize, also known as the Humboldt Research Award, is an award given by the Alexander von Humboldt Foundation to internationally renowned scientists and scholars, and is currently valued at € 60,000 with the possibility of further support during the prize winner's life. Up to one...
(2008). - Doctor Honoris Causa University Maria Sklodowska-Curie, Lublin, Poland (2008).
External links
- http://ernstbauer.physics.asu.edu Web page of Ernst Bauer at Arizona State University.