Table Of ContentTREATISE ON
SOLID STATE CHEMISTRY
Volume6A
Surfaces I
TREATISE ON SOLID STATE CHEMISTRY
Volume 1 • The Chemical Structure of Solids
Volume 2 • Defects in Solids
Volume 3 • Crystalline and Noncrystalline Solids
Volume 4 • Reactivity of Solids
Volume 5 • Changes of State
Volume 6A • Surfaces I
Volume 6B • Surfaces II
TREATISE ON
SOLID STATE CHEMISTRY
Volume6A
Surfaces I
Edited by
N.B. Hannay
Vice President
Research and Patents
Bell Laboratories
Murray Hill, New Jersey
PLENUM PRESS • NEW YORK-LONDON
Library of Congress Cataloging in Publication Data
Hannay, Norman Bruce, 1921-
Treatise on solid state chemistry.
Includes bibliographical references.
CONTENTS: v. 1. The chemical structure of solids. -v. 2. Defects in solids. -v. 3.
Crystalline and noncrystalline solids. -v. 4. Reactivity of solids. -v. 5. Changes of
state. -v. 6A. Surfaces I. -v. 6B. Surfaces II.
1. Solid state chemistry. I. Title.
QD478.H35 541'.0421 73-13799
ISBN-13: 978-1-4613-4315-8 e-ISBN-13: 978-1-4613-4313-4
DOl: 10.1007/978-1-4613-4313-4
© 1976 Bell Telephone Laboratories, Incorporated
Softcover reprint of the hardcover 1st edition 1976
Published by Plenum Press, New York
A Division of Plenum Publishing Corporation
227 West 17th Street, New York, N.Y. 10011
All righ ts reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted,
in any form or by any means, electronic, mechanical, photocopying, microfilming,
recording, or otherwise, without written permission from the Publisher
Foreword
The last quarter-century has been marked by the extremely rapid growth of
the solid-state sciences. They include what is now the largest subfield of
physics, and the materials engineering sciences have likewise flourished.
And, playing an active role throughout this vast area of science and engineer
ing have been very large numbers of chemists. Yet, even though the role of
chemistry in the solid-state sciences has been a vital one and the solid-state
sciences have, in turn, made enormous contributions to chemical thought,
solid-state chemistry has not been recognized by the general body of chemists
as a major subfield of chemistry. Solid-state chemistry is not even well
defined as to content. Some, for example, would have it include only the
quantum chemistry of solids and would reject thermodynamics and phase
equilibria; this is nonsense. Solid-state chemistry has many facets, and one
of the purposes of this Treatise is to help define the field.
Perhaps the most general characteristic of solid-state chemistry, and
one which helps differentiate it from solid-state physics, is its focus on the
chemical composition and atomic configuration of real solids and on the
relationship of composition and structure to the chemical and physical
properties of the solid. Real solids are usually extremely complex and exhibit
almost infinite variety in their compositional and structural features.
Chemistry has never hesitated about the role of applied science, and
solid-state chemistry is no exception. Hence, we have chosen to include in the
field not only basic science but also the more fundamental aspects of the
materials engineering sciences.
The central theme of the Treatise is the exposition of unifying principles
in the chemistry, physical chemistry, and chemical physics of solids. Examples
are provided only to illustrate these principles. It has, throughout, a chemical
viewpoint; there is, perforce, substantial overlap with some areas of solid-
v
Foreword
state physics and metallurgy but a uniquely chemical perspective underlies
the whole. Each chapter seeks to be as definitive as possible in its particular
segment of the field.
The Treatise is intended for advanced workers in the field. The scope
of the work is such that all solid-state chemists, as well as solid-state scientists
and engineers in allied disciplines, should find in it much that is new to them
in areas outside their own specializations; they should also find that the
treatment of their own particular areas of interest offers enlightening
perspectives.
Certain standard subjects, such as crystal structures, have been omitted
because they are so well covered in many readily available standard references
and are a part of the background of all solid-state scientists. Certain limited
redundancies are intended, partly because they occur in different volumes of
the series, but mainly because some subjects need to be examined from
different viewpoints and in different contexts. The first three volumes deal
with the structure of solids and its relation to properties. Volumes 4 and 5
cover broad areas of chemical dynamics in bulk solids. Volume 6 treats both
structure and chemical dynamics of surfaces.
N.B.H.
VI
Preface to Volume 6A
No area of solid-state science offers greater promise of new funda
mental understanding, as well as of the development of a new and
firm base for the applied science, than does the study of surfaces.
An array of powerful new experimental and theoretical tools has been
developing in the last several years. They can add immensely to our
insights over a range of surface phenomena, ranging from the desired
(catalysis, epitaxy, electrochemical reactions, etc.) to the unwanted
(corrosion, oxidation). In Volumes 6A and 6B are covered not only
the major surface phenomena, but also the new experimental and
theoretical techniques for the study of surfaces.
vii
Contents of Volume 6A
Chapter 1
The Structure and Thermodynamics of Clean Surfaces-Principles 1
G. A. Somorjai
1. Introduction............................................ 1
2. Thermodynamics of Surfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Estimation of Specific Surface Free Energies. . .. . . . . . . .. 7
2.2. The Effect of Surface Tension on Growth and Surface
Reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3. Surface Tension of Multicomponent Systems. . . . . . . . . . . 13
2.4. The Surface Composition of an Ideal Binary Solution. . . . 14
2.5. Thermodynamic Properties of Curved Surfaces. . . . . . .. . 16
3. The Structure of Surfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4. The Atomic Structure of Clean Surfaces. . . . . . . . . . . . . . . . . . . . 24
4.1. Nomenclature..................................... 24
4.2. Unreconstructed Surfaces That Exhibit Contraction (Ex
pansion) Perpendicular to the Surface Plane or Changes
in Chemical Composition. . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.3. Surface Reconstruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.4. Stepped High-Miller-Index Surfaces. . . . . . . . . . . . . . . . . . . 36
4.5. Detection of Surface Disorder on an Atomic Scale. . . . . . 41
5. The Electronic Structure of Surfaces. . . . . . . . . . . . . . . . . . . . . . . . 44
5.1. The Theory of Electron Surface States. . . . . . . . . . . . . . . . . 48
5.2. Chahges of Work Function. . . . . . . . . . . . . . . . . . . . . . . . . . 50
5.3. The Studies of Electronic Structure at Surfaces by Emission
and Recombination Involving Inner Shell Electrons. . . . . 50
Acknowledgment. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 53
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
lX
Contents of Volume 6A
Chapter 2
Surface Structure-Experimental Methods 57
E. G. McRae and H. D. Hagstrum
1. Introduction............................................ 57
1.1. Scope and Organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
1.2. Importance of Surface Purity and Surface Order. . . . . . . . 59
1.3. Experimental Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
2. Chemical Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.1. Core-Level Spectroscopies. . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.2. Ion Scattering Spectroscopy. . . . . . . . . . . . . . . . . . . . . . . . . . 73
2.3. Secondary Ion Emission and Desorption Methods. . . . . . . 81
3. Geometric Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.1. Field Ion Microscopy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.2. Reflection Electron Diffraction. . . . . . . . . . . . . . . . . . . . . . . 84
3.3. Ion and Atom Scattering. . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
3.4. High-Resolution Electron Spectroscopy. . . . . . . . . . . . . . . . 109
4. Surface Electronic Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
4.1. Characterization of Electronic Structure. . . . . . . . . . . . . . . II 0
4.2. Kinds of Experimental Methods. . . . . . . . . . . . . . . . . . . . . . III
4.3. Electron Spectroscopies for Filled States. . . . . . . . . . . . . . . III
4.4. Electron Spectroscopies for Unfilled States. . . . . . . . . . . . . 119
4.5. Basic Characteristics of Surface Electron Spectroscopies 122
4.6. Optical Methods of Studying Surface Electronic Structures 142
4.7. Methods Based on the Semiconductor Space-Charge Layer 143
4.8. Inelastic LEED and Surface Plasmon Dispersion. . . . . . . . 150
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Chapter 3
Evaporation from Solids 165
Gerd M. Rosenblatt
1. Introduction............................................ 165
2. Principles.............................................. 169
2.1. Introduction to Kinetic Principles. . . . . . . . . . . . . . . . . . . . . 169
2.2. Vaporization, Condensation, and Thermal Accommoda-
tion Coefficients. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
2.3. Introduction to Thermodynamic Principles. . . . . . . . . . . . . 188
2.4. Free Evaporation. . . . .. . . . . . . . . . . . . . . . . . . . .. . .. . . . . . 195
2.5. Systems with More than One Vapor Species. . . . . . . . . . . . 206
3. Experimental Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
3.1. Measurements of Vaporization Rates Far from Equilib-
rium. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . 212
3.2. Measurements of Vaporization Rates Near Equilibrium. . 218
x
Contents of Volume 6A
3.3. Measurements of Vaporization Coefficients.. . . . . . . . . . . . 221
3.4. Supplemental Experiments. . . . . . . . . . . . . . . . . . . . . . . . . . . 222
4. Evaporation Mechanisms of Single Crystals. . . . . . . . . . . . . . . . . 223
4.1. The Terrace-Ledge-Kink Model. . . . . . . . . . . . . . . . . . . . . . 223
4.2. Elements and Isotropic Molecular Solids. . . . . . . . . . . . . . . 227
4.3. Nondissociating Ionic Solids. . . . . . . . . . . . . . . . . . . . . . . . . 228
4.4. Dissociating Solids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
4.5. Associating Vapors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
5. Sources ofInformation on Evaporation Rates. . . . . . . . . . . . . . . 237
5.1. Compilations of Vaporization Coefficients for Solids. . . . . 237
5.2. Sources of Vapor Pressure Data for Solids. . . . . . . . . . . . . 238
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Re~rences.............................................. 238
Chapter 4
Molecular Beam Deposition of Solids on Surfaces: Ultrathin Films 241
R. J. H. Voorhoeve
1. Introduction............................................ 241
2. Kinetic Impediments for Condensation. . . . . . . . . . . . . . . . . . . . . 244
2.1. Atom-Surface Interaction. . . . . . . . . . . . . . . . . . . . . . . . . . . 244
2.2. Molecule-Surface Interaction. . . . . . . . . . . . . . . . . . . . . . . . 248
3. Nucleation of Solids and Liquids on Surfaces: Theory. . . . . . . . 249
3.1. Adsorption and Nucleation: Classification of Interfacial
Interactions into Four Types. . . . . . . . . . . . . . . . . . . . . . . . . 249
3.2. Type I Deposition: Weak Interaction with the Substrate. 253
3.3. Type II Deposition: :·,iedium Strong Interaction with the
Substrate and Small Lattice Mismatch. . . . . . . . . . . . . . . . . 267
3.4. Type III Deposition: Strong Interaction, Large Misfit;
and Type IV, Reactive Deposition. . . . . . . . . . . . . . . . . . . . 271
3.5. Computer Simulation of Vapor Deposition. . . . . . . . . . . . . 272
4. Experimental Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
4.1. Molecular Beam Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . 274
42. In Situ Transmission Electron Microscopy ...... '. . . . . . . 277
4.3. Scanning High-Energy Electron Diffraction (SHEED) . . . 279
4.4. Multiple Ion Reflection.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
4.5. Field Ion Microscopy (FIM) and Field Emission Micros-
copy (FEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
5. Deposition of Semiconductors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
5.1 . Silicon............................................ 281
5.2. Germanium....................................... 285
5.3. Gallium Arsenide and Gallium Phosphide. . . . . . . . . . . . . . 287
5.4. II-VI Compound Semiconductors. . . . . . . . . . . . . . . . . . . . 289
6. Deposition of Metals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
6.1. Deposition onto Ionic Substrates and Layered Compounds 289
Xl
