Polycrystalline Semiconductors: Physical Properties and Applications: Proceedings of the International School of Materials Science and Technology at the Ettore Majorana Centre, Erice, Italy, July 1–15, 1984

254 Pages·1985·8.397 MB·English

by  A. Bourret (auth.), Dr. Günther Harbeke (eds.)

57
Springer Series in Solid-State Sciences
Edited by Manuel Cardona
Springer Series in Solid-State Sciences
Editors: M. Cardona P. Fulde H.-J. Queisser
40 Semiconductor Physics - 50 Multiple Diffraction of X-Rays in Crystals
An Introduction By K Seeger By Shih-Lin Chang
41 The LMTO Method 51 Phonon Scattering in Condensed Matter
Muffin-Tin Orbitals and Electronic Editors: W. Eisenmenger, K LaBmann,
Structure and S. D5ttinger
By H. L. Skriver
52 Superconductivity in Magnetic and Exotic
42 Crystal Optics with Spatial Dispersion,
Materials
and Excitons
Editors: T. Matsubara and A Kotani
By V. M. Agranovich and V. L. Ginzburg
53 Two-Dimensional Systems,
43 Resonant Nonlinear Interactions of
Heterostructures, and Superiattices
Light with Matter
Editors: G. Bauer, F. Kuchar,
By V. S. Butylkin, A E. Kaplan,
and H. Heinrich
Yu. G. Khronopulo, and E. I. Yakubovich
44 Elastic Media with Microstructure II 54 Magnetic Excitations and Fluctuations
Three-Dimensional Models Editors: S. Lovesey, U. Balucani, F. Borsa,
ByI.A Kunin and V. Tognetti
45 Electronic Properties of Doped 55 The Theory of Magnetism II.
Semiconductors Thermodynamics and Statistical Mechanics
By B.!. Shklovskii and A L. Efros By D. C. Mattis
46 Topological Disorder in Condensed Matter 56 Spin Fluctuations in Itinerant Electron
Editors: F. Yonezawa and T. Ninomiya Magnetism By T. Moriya
47 Statics and Dynamics of Nonlinear
57 Polycrystalline Semiconductors,
Systems
Physical Properties and Applications
Editors: G. Benedek, H. Bilz,
Editor: G. Harbeke
and R Zeyher
48 Magnetic Phase Transitions 58 The Recursion Method and
Editors: M. Ausloos and R J. Elliott Its Applications
Editors: D. Pettifor and D. Weaire
49 Organic Molecular Aggregates, Electronic
Excitation and Interaction Processes 59 Dynamical Processes and
Editors: P. Reineker, H. Haken, Ordering on Solid Surfaces
and H.C. Wolf Editors: A Yoshimori and M. Tsukada
Volume 1-39 are listed on the back inside cover
Polycrystalline
Semiconductors
Physical Properties and Applications
Proceedings of the International School
of Materials Science and Technology
at the Ettore Majorana Centre, Erice, Italy,
July 1-15, 1984
Editor: G. Harbeke
With 159 Figures
Springer-Verlag
Berlin Heidelberg New York Tokyo 1985
Dr. GUnther Harbeke
Laboratories RCA Ltd., Badenerstr. 569
CH-8048 ZUrich, Switzerland
Series Editars:
Professor Dr. Manuel Cardona
Professor Dr. Peter Fulde
Professor Dr. Hans-Joachim Queisser
Max-Planck-Institut flir Festk6rperforschung, Heisenbergstrasse 1
D-7000 Stuttgart 80, Fed. Rep. of Germany
ISBN-13: 978-3-642-82443-2 e-ISBN-13: 978-3-642-82441-8
DOl: 10.1007/978-3-642-82441-8
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Preface
In terms of structure, the field of semiconductors spans a wide range, from
the perfect order of single crystals to the non-periodic, disordered amorph
ous state. The two extremes of this range attract a large amount of inter
est. On one side, glamorous novel phenomena are being found which can only
occur in specially tailored ultra-perfect periodic lattices. On the other
side, the exotic and challenging nature of the amorphous state has triggered
a surge of activity in recent years.
Po1ycrystall i ne semi conductors are in between. They are among the work
horses in the field, useful in many applications, a handy solution to many
practical problems and still - they have not received in the past the amount
of research interest that they deserve. It is the aim of the present book to
improve this situation. The book originated from the lectures and seminars
presented at the course on "Po1ycrystall i ne Semi conductors - Physical
Properties and Applications" of "the International School on Materials Scien
ce and Technology, hel d at the Centre for Sci entifi c Culture "Ettore
Majorana" in Erice, Italy, July 1-15, 1984.
The physics of polycrystalline semiconductors is largely the physics of
grain boundaries. Grain boundaries play an essential part in polycrystal1ine
semiconductors. The charge carriers perhaps see themselves in the role of
the traveller in ancient times who could fairly easily traverse wide areas
of flat country or long stretches of a calm sea but had great difficulties
in crossing steep mountain ridges and deep river gorges.
The present volum? is divided into four parts. In the first part, the
fundamental aspects of the physics of grain boundaries are laid out. The use
of modern research techniques has greatly increased our knowledge about the
detailed atomic structure of grain boundaries and the type of defects which
may exist in them. This knowledge forms the basis for total energy calcula
tions and facilitates the discussion of atom migration phenomena. In the se
cond part, the present state of electronic characterization of grain
boundaries is reviewed. The authors deal with the important issues of elec
tronic states at and charge transport across grain boundaries. One of the
major objectives of these studies is to establish a relationship between the
electronic properties of a single boundary in a bi-crystal (ideal situation,
easier to study) and those of fil ms with a vi rtually i nfi nite nunber of
grain boundaries (real situation, of practical interest).
The remaining two parts are mainly devoted to a discussion of the physics
involved in using po1ycrystalline semiconductors as parts of active or pas
sive electronic and optoelectronic devices. Po1ycrystalline silicon offers
the invaluable advantage of a high degree of interfacial compatibility with
single crystal silicon and silicon dioxide in microelectronics. Besides its
crucial function in integrated-circuit technology it is also a key material
v
for polycrystalline solar cells. Polycrystalline structures of semiconduc
ting compounds such as ZnS and various oxides have found their place in the
technology of electroluminescent displays or sensors and varistors,
respecti vely . All the chapters on devi ce physi cs stress the necessi ty of a
fruitful exchange between fundamental aspects, materials characterization
and the technological application. This fruitful exchange became a major
achievement of the Erice lecture course, as is reflected in this book.
I wish to thank all lecturers and participants for their stimulating con
tributions to the success of the course and to the present book. We all have
expressed our appreciation for the fine facilities afforded us by the Ettore
Majorana Centre and are indebted to its Director, Professor A. Zichichi, to
Dr. A. Gabriele, Dr. Pinola Savalli and the staff of the Centre. I am grate
ful for the generous support, in particular for student grants, given by the
sponsoring institutions European Physical Society, European Research Office,
General Electric Co. Wembley, IBM Italia, Italian Ministry of Education,
Italian Ministry of Scientific and Technological Research, Italian CNR Group
of the Structure of Matter, Laboratories RCA Zurich, Sicilian Regional Go
vernment and Siemens AG Munich. Last but not least, I appreciate the advice
of the Director of the School, Professor M. Balkanski, and of many friends
and colleagues in the field of semiconductors.
Zurich, Switzerland Gunther Harbeke
December 1984
VI
Contents
Part I Fundamental Aspects of Grain Boundaries
Atomic Structure of Grain Boundaries. By A. Bourret (With 5 Figures) 2
Computer Calculations of Grain Boundary Energies in Germanium and
Silicon. By H.J. Moller and H.H. Singer (With 4 Figures) ............. 18
The Geometrical Character of Extended Interfacial Defects in
Semiconducting Materials. By R.C. Pond (With 12 Figures) .............. 27
Grain Boundary Segregation. Grain Boundary Diffusion
By M. Aucouturier (With 22 Figures) ......................••.......... 47
Part /I Electronic Characterization of Grain Boundaries
Electronic Properties of Grain Boundaries
By J. Werner (With 15 Figures) ....................................... 76
Electronic States at Grain Boundaries in Semiconductors
By A. Broni atowski (With 15 Fi gures) .. .. .. .. .. . .. .. .. .. . .. .. .. .. .. .. . 95
Electrical Properties of Grain Boundaries in the Presence of Deep Bulk
Traps. By G. Blatter and F. Greuter (With 7 Figures) ................. 118
Beam Induced Current Characterization in Polycrystalline Semiconductors
By C. Donolato (With 17 Figures) ..................................... 138
Part /II Properties and Applications of Polycrystalline Silicon
Optical Properties of Polycrystalline Silicon Films
By G. Harbeke (With 10 Fi gures) .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .... 156
Polycrystalline Silicon in Integrated Circuits
By H.C. de Graaff (With 13 Figures) .................................. 170
VII
Part I V Applications of Polycrystalline Semiconductor Compounds
Electroluminescence in Polycrystalline Semiconductors
By R. Mach (With 21 Figures) ......•.•.••.••.......••...•.••..•..•.••. 186
The Electrical Properties of Oxides Under Conditions of Oxidation,
Reduction and Catalysis. By S. Strassler, A. Reis, and D. Wieser 209
Evolution of Physical Models for ZnO-Varistors - A Review
By R. Einzinger (With 18 Figures) •..•.•.•.•.•..••.••.••..•.••••••••.. 228
Index of Contributors •••••••..•••••••••••••••..•••••••..••..••••••••. 245
VIII
Part I
Fundamental Aspects of
Grain Boundaries
Atomic Structure of Grain Boundaries
A. Bourret
Departement de Recherche Fondamentale - Physique du Solide, CEN-Grenoble
F-85 X-38041 Grenoble Cedex, France
ABSTRACT The geometrical description of a general grain boundary in a crys
talline structure is first summarized. This includes the definition of the
coincidence site lattice (CSL) at particular twin angles and the DSC lattice.
Then the dislocation modelling is presented using primary and secondary
dislocations. However it is emphasized that this description is not unique.
Therefore it is necessary to introduce the structural unit model which
describes the core structure of the boundary. A detailed description of these
units in cubic diamond structure and their relation to dislocation core
structure will be given. A review of the experimental techniques giving some
information on atomic structure is made. Few selected examples particularly
using the high resolution electron microscopy technique are used to illustra
te the different theoretical approaches with emphasis on the structural
unit model. It is concluded that our knowledge of the atomic structure of
grain boundary in semiconductors is still incomplete.
1. INTRODUCTION
Grain boundaries ~.B~ are one of the most common two dimensional extended
defects in crystals. Their influence on a large variety of physical proper
ties of materials has been largely recognized. Firstly emphasis was given to
the influence of GB on mechanical properties at high temperature (G.B. creep
or sliding), or on transport properties (enhanced diffusion along G.Bs). In
semiconductors their influence on electrical properties is of prime impor
tance since the growing interest in employing cheap polycrystalline sili
con. It was remarked for a long time, that some G.Bshave practically no
effect on electron mobility, although some others have a deleterious effect
and affect the efficiency of photovoltaic solar cell : it was clear that
such differences should be attributed to the local structure of the G.B.
The earliest ideas on the G.B. atomistic structure were given by Rosenhaim
and Humphrey [1] who proposed that an amorphous layer is present between the
two crystals. Although this old model was discarded for many years it has
been proved to be valid in some multicomponent ceramics and sintered powder
[2]. However in all other cases and specially in metals or semiconductors it
rapidly became evident that GBs were closely related to the crystalline na
ture of the material : for instance the orientation dependence of many
macroscopic properties is well established. Hargreaves and Hills [8] first
proposed models based on a periodic medium at the G.B. interface composed of
one atomic plane occupying intermediate positions right between the two
crystals (transition lattice theory). Then Mott [9] proposed the island mo
del with region of good fit separated by region of poor fit. One of the
first observations byetch pit or copper decoration of small angle G.B.in se
miconductors [3] gave a firm basis to the idea proposed originally by Burgers
[10] that a sub G.B.is composed of a regular array of dislocations. This was
formalized by Brandon et al. [11] and developed further by Bollmann [4]
2