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Semiconductor Surface Physics

EDITED BY R. H. KINGSTON
E. Burstein
A. L. McWhorter
P. H. Miller
D. T. Stevenson
P. B. Weisz
Copyright Date: 1957
Pages: 432
http://www.erys2.com/stable/j.ctv512sg7
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  • Book Info
    Semiconductor Surface Physics
    Book Description:

    Proceedings of the Conference on the Physics of Semiconductor Surfaces, June 1956.

    eISBN: 978-1-5128-0305-1
    Subjects: Physics, Chemistry

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. FOREWORD
    (pp. v-vi)
    R. H. K.

    The Conference on the Physics of Semiconductor Surfaces was brought about through the efforts of the Office of Naval Research and it was the enthusiasm of Julius L. Jackson of that organization which led to the formation of the conference committee in the late summer of 1955. The committee consisted of:

    J. L. Jackson, Office of Naval Research, Arrangements and Invitations

    R. H. Kingston, Lincoln Laboratory, Program and Publications

    P. H. Miller, Jr., University of Pennsylvania, Local Arrangements and Publications

    J. Bardeen, University of Illinois

    W. H. Brattain, Bell Telephone Laboratories

    E. Burstein, Xavai Research Laboratory

    C. G. B. Garrett,...

  3. INTRODUCTION
    (pp. vii-xiv)
    R. H. Kingston

    Without question the recent marked interest in the physics of semiconductor surfaces has arisen from the numerous problems encountered by the solid-state physicist in understanding those properties of semiconductor structures controlled by the surface treatment and ambient. One has only to consider the pronounced difference in sensitivity of a metal and a semiconductor to appreciate the importance of the surface boundary. Consider, for example, a layer of accumulated charge of 1015electrons per cm2 on the surface of a solid, or approximately one charge per lattice site. If the material is a metal, with the order of 1022free carriers...

  4. Table of Contents
    (pp. xv-xvi)
  5. I. CLEAN SURFACES

    • LOW-ENERGY ELECTRON DIFFRACTION STUDIES OF CLEANED AND GAS-COVERED GERMANIUM (100) SURFACES
      (pp. 3-22)
      R. E. SCHLIER and H. E. FARNSWORTH

      The properties of clean surfaces are of considerable interest to investigators of surface phenomena. A better understanding of the properties of semiconductor surfaces can be gained through experimental work on clean and controllably contaminated surfaces. This requires a clean surface which remains stable for an appreciable time, so that it may be exposed to known contaminants under controlled conditions. Techniques of ultra-high vacuum production and measurement, such as those developed by Alpert,1 make possible the necessary stability; the remaining problems are to prepare and to identify clean surfaces.

      Although it is expected that cathode sputtering will remove surface contamination in...

    • ELECTRICAL PROPERTIES OF A CLEAN GERMANIUM SURFACE
      (pp. 23-52)
      PAUL HANDLER

      The existence of localized surface states in crystals was first suggested by Tamm1 in 1932 on the basis of a study of a special one-dimensional model. A more general treatment of a one-dimensional model by Shockley2 in 1939 showed that surface states can occur only if there is a separate potential trough at the surface or if the energy bands arising from separate atomic levels overlap. In generalizing his results, Shockley concluded that surface states should occur in the forbidden region between the highest filled band and the lowest vacant band of germanium, since this gap occurs as a result...

  6. II. REAL SURFACES

    • MOBILITY IN INVERSION LAYERS: THEORY AND EXPERIMENT
      (pp. 55-69)
      J. R. SCHRIEFFER

      In considering the flow of carriers in a macroscopic semiconductor specimen, one usually takes the normal bulk scattering mechanism into account and neglects the collisions of the carriers with the surface. Such a procedure is in general valid only when one is not specifically interested in the flow of carriers near the surface. In recent years, many problems have arisen in which the behavior of the carriers near the surface plays a dominant role, for example the channel effect1-5and the field effect6-9. The analysis of the experimental data on these effects depends rather critically upon the mobility of the...

    • FIELD EFFECT ON SURFACE CONDUCTANCE AND SURFACE RECOMBINATION
      (pp. 70-84)
      P. C. BANBURY, G. G. E. LOW and J. D. NIXON

      The measurements to be described in this paper concern the effect of capacitively applied electric fields on surface conductance and surface recombination in germanium crystals. Observations of the field effect on conductance were first reported by Shockley and Pearson1 using evaporated films, and subsequently a number of investigations have been carried out on single crystal specimens using alternating fields.2,3

      The work on surfaces in this laboratory has been primarily concerned with measurements obtained using short voltage pulses or switched dc voltages. The general form of the conductance effect under these conditions and its qualitative interpretation have been discussed by Low.?...

    • SURFACE RECOMBINATION PROCESSES IN GERMANIUM AND THEIR INVESTIGATION BY MEANS OF TRANSVERSE ELECTRIC FIELDS
      (pp. 85-107)
      A. MANY, E. HARNIK and Y. MARGONINSKI

      It is well known that the equilibrium between holes and electrons in a semiconductor can be displaced by various external stimuli, e.g. by illumination or by contact injection of minority carriers. After the cessation of the external stimulus, the equilibrium relations are restored by processes which are in many cases exponential and can be described in terms of a single decay constant. The effective lifetime so determined is made up of two contributions which arise from bulk and surface recombination. If the bulk life time is known and not too small, measurement of the effective lifetime of the minority carriers...

    • SHORT CONTRIBUTION: STORAGE OF INJECTED CARRIERS AT SURFACES OF GERMANIUM
      (pp. 108-110)
      B. H. SCHULTZ

      Injection of electron-hole pairs in germanium near the surface is accompanied by an increase of the concentrations of the particles in the space charge layer and also of those in the surface states. It is usually assumed that for rapidly changing concentrations, the holes in the “fast acceptor surface states” remain in equilibrium with the holes in the valence band at the surface and also with the holes in the bulk close to the surface, whereas the holes in the “slow surface states,” or the “surface ionic charges” do not follow the rapid fluctuations. A similar assumption is made for...

    • FIELD EFFECT AND PHOTO EFFECT EXPERIMENTS ON GERMANIUM SURFACES. 1. EQUILIBRIUM CONDITIONS WITHIN THE SEMICONDUCTOR
      (pp. 111-125)
      W. L. BROWN, W. H. BRATTAIN, C. G. B. GARRETT and H. C. MONTGOMERY

      We are concerned with the properties of germanium surfaces which have been prepared by etching and are subsequently exposed to various gaseous ambients at substantially atmospheric pressure. One would ultimately like to understand the physical and chemical origin of the electronic surface states which appear with this surface preparation. As yet the answer to this question is entirely in the realm of speculation, and the immediate problem is one of describing the properties of the states as they exist. A complete characterization would at least include the energy distribution of the electronic states in the forbidden energy gap at the...

    • FIELD EFFECT AND PHOTO EFFECT EXPERIMENTS ON GERMANIUM SURFACES. 2. NON-EQUILIBRIUM CONDITIONS WITHIN THE SEMICONDUCTOR
      (pp. 126-138)
      C. G. B. GARRETT, W. H. BRATTAIN, W. L. BROWN and H. C. MONTGOMERY

      The preceding paper contains a discussion of measurements of field effect on germanium surfaces under conditions in which there is a thermodynamic equilibrium within the semiconductor. This paper is concerned with various experiments on germanium surfaces for which the thermodynamic equilibrium between holes and electrons in the semiconductor has been upset. For the purposes of these papers “equilibrium inside the semiconductor” means that the productnpof the electron and hole density is everywhere equal to the equilibrium value$n_{1}^{2}$. Evidently this condition is well satisfied in experiments on the modulation of surface conductivity and surface capacity by external...

    • MEASUREMENTS OF INVERSION LAYERS ON SILICON AND GERMANIUM AND THEIR INTERPRETATION
      (pp. 139-168)
      H. STATZ, G. A. DE MARS, L. DAVIS JR. and A. ADAMS JR.

      Inversion layers are thin layers (10-4to 10-6cm) of semiconductor material just below the surface which have a different conductivity type than the bulk of the material. Thus, a thinp-type layer onn-type material or a thinn-type layer onp-type material will be called an inversion layer. The inversion layers which will be considered in this article result not from a different doping of a thin surface layer but rather from a net electric charge on the surface. Obviously, a net negative charge on ann-type semiconductor or a net positive charge on ap-type semiconductor can...

    • SLOW RELAXATION PHENOMENA ON THE GERMANIUM SURFACE
      (pp. 169-196)
      S. ROY MORRISON

      It has been concluded by many investigators1-8that there are two sets of surface states on the germanium surface. These have been termed “fast” states and “slow” states. The fast states have trapping time con tants he order of fractions of a millisecond. The slow states exhibit relaxation times at room temperature the order of seconds to minutes. It is generally believed that the fast surface states are located at the interface between the germanium and the layer of germanium oxide. The slow states are probably located at the outer surface of the oxide. It is thus believed the long...

    • EFFECTS OF THICK OXIDES ON GERMANIUM SURFACE PROPERTIES
      (pp. 197-206)
      M. LASSER, C. WYSOCKI and B. BERNSTEIN

      The existence of surface states at the surface of a germanium crystal has been well established. However, there is still much to be learned about the origin of these states and their interaction with the region immediately under the surface.

      Surface states could conceivably originate in a number of ways:

      (1) The termination of the lattice with germanium bonds not joined one to the other in the same manner as in the bulk of the material, giving rise to different energy states at the germanium-germanium oxide interface.

      (2) Imperfections or impurities arising at either the germanium-germanium oxide interface or throughout...

    • 1/f NOISE AND GERMANIUM SURFACE PROPERTIES
      (pp. 207-228)
      A. L. MCWHORTER

      As has been discussed in several of the preceding papers,1-4recent experiments on germanium surfaces have shown that in addition to the fast-acting surface recombination centers there exists a set of slowly-acting surface states with relaxation times of the order of seconds and minutes. The surface recombination states are presumed to be located at the germanium-germanium oxide interface, while the slow states probably lie in or on the outside of the oxide layer. In this paper we will show how fluctuations in the number of charges in these slow states might account for the so-called excess or 1/fnoise found...

    • SURFACE STUDIES ON PHOTOCONDUCTIVE LEAD SULFIDE FILMS
      (pp. 229-237)
      R. L. PETRITZ, F. L. LUMMIS, H. E. SORROWS and J. F. WOODS

      Fundamental semiconductor surface studies have been mainly centered on germanium and silicon. It is of interest to see if the basic ideas that have been developed are applicable to other semiconductors. A reasonably complete picture of the bulk properties of lead sulfide has been developed. The intrinsic energy gap is known to be 0.34 ev,1,2the scattering of holes and electrons has been studied,3 donor and acceptor levels have been shown to result from deviations from stoichiometry2 as well as from impurity atoms.? The details of the energy bands are less understood than for germanium, although the first theoretical wave...

    • SURFACE STUDIES ON CLEAVED CRYSTALS OF LEAD SULFIDE
      (pp. 238-244)
      W. W. SCANLON

      A clean surface on a semiconductor crystal may be obtained by two different methods. In the first, currently used for germanium, one starts out with an initially dirty surface and tries to clean it by various ion bombardments, baking and annealing treatments in ultra high vacuum. In the second, which will be the subject of this paper, one starts out with an initially clean surface as obtained by cleavage of a crystal and tries to prevent it from becoming dirty.

      It is generally agreed that a cleaved surface provides the nearest approach to an ideally clean surface. Germanium does not...

  7. III. ADSORPTION AND CATALYSIS

    • INTRODUCTORY REMARKS: BRIDGES OF PHYSICS AND CHEMISTRY ACROSS THE SEMICONDUCTOR SURFACE
      (pp. 247-258)
      P. B. WEISZ

      The introduction of this session marks a rather unusual meeting of investigators from fields of physics and of chemistry. It takes place around a subject which is becoming increasingly recognized as one of mutual interest and importance: the boundary of the solid. Thephysicist’sattention was drawn to it mainly due to the influence of the boundary on the behavior of the atmosphere of electrical carriers, electrons and holes within the solid. On the other hand, thechemisthas been concerned with its influence on the atmosphere of atoms and moleculesexternallysurrounding the solid.

      It is appropriate at an...

    • GAS REACTIONS ON SEMICONDUCTING SURFACES AND SPACE CHARGE BOUNDARY LAYERS
      (pp. 259-282)
      KARL HAUFFE

      In all chemical processes which are accelerated by catalysts, the electronic interaction of the catalyst with the reacting molecules (initial substances, intermediate products and end products) plays a decisive role. In this connection the electronic interaction may manifest itself exclusively in polarization, or also frequently in a direct electron exchange. Experimental proof of the electron exchange between catalyst and reacting gases was provided some time ago by Wagner and Hauffe1 for the decomposition of N2O and the CO oxidation on oxides (NiO, CuO). The problem was again taken up only ten years later and dealt with more intensively by other...

    • EXPERIMENTS CONNECTING SEMICONDUCTOR PROPERTIES AND CATALYSIS
      (pp. 283-296)
      GEORGE-MARIA SCHWAB

      Semiconductors are generally subdivided into impurity and intrinsic semiconductors. In the former, the forbidden zone is so broad (> 1 ev) that electrons cannot cross it by thermal energy in the normal lattice. However, localized donor terms can be inserted within the forbidden zone near the conductivity level either by impurities or by reversible or irreversible electronic disorder (n-type conductors). Equally, acceptor terms can be produced in the same way near the lower edge of the forbidden zone (p-type conductors). E.g. NiO is ap-type conductor because in thermal disorder it contains excess oxygen and therefore some Ni3+ions as...

    • LONG TIME WORK FUNCTION CHANGES INDUCED BY LIGHT AND ELECTROSTATIC FIELDS
      (pp. 297-324)
      G. W. PRATT JR. and H. H. KOLM

      One of the classic tools used to study surface phenomena is the measurement of the work function. Any process which changes the potential barrier at the surface can be directly monitored by this technique. It has proven to be particularly useful in investigating the nature of the electronic interaction between chemisorbed atoms and the adsorbent surface. One can get information as to how the chemisorption bond is formed and as to its final form. The work function plays an important role in the electron transfer processes involved in adsorption and consequently in the kinetics and heat of reaction. In accord...

  8. IV. OXIDATION

    • THE OXIDATION OF METALS
      (pp. 327-348)
      N. CABRERA

      Several reviews on the theory of oxidation of metals have recently appeared which cover most of the developments in this field, so that a further discussion would at first sight appear unnecessary. Among them, one should mention, first of all, the book by K. Hauffe1 and also the papers by Grimley and Stone in the book on Chemistry of the Solid State edited by W. E. Garner.2 The present author feels, however, that these reviews have not sufficiently emphasized the relationship of the formation of an oxide to the more general theory of the growth of a phase according to...

    • THE INTERACTION OF OXYGEN WITH CLEAN GERMANIUM SURFACES: 1. EXPERIMENT
      (pp. 349-361)
      M. GREEN, J. A. KAFALAS and P. H. ROBINSON

      The surface oxidation of germanium is of considerable interest because the electrical behavior of a germanium surface cannot be thoroughly understood without a knowledge of the surface chemistry. This paper deals chiefly with the results of a study of the kinetics,1 and of the heat of adsorption, of oxygen on clean germanium surfaces.

      The kinetics of oxygen take-up on germanium were studied using an apparatus of the type shown in Fig. 1. The virgin surface were producedin situby crushing single crystal disks under the glass drop-hammer: here advantage was taken of the fact that germanium is brittle and...

    • THE INTERACTION OF OXYGEN WITH CLEAN GERMANIUM SURFACES: 2. THEORETICAL DISCUSSION
      (pp. 362-382)
      MINO GREEN

      The interaction of oxygen gas with virgin surfaces of a number of different metals1 and germanium2 has been the subject of recent investigations. These have disclosed an apparently new category of interaction process leading to ultra-thin oxide films, just a little beyond monolayer formation. Here the experimental data obtained for the germanium-oxygen system are examined. The possibility of establishing various diagnostic criteria for different interaction mechanisms is also considered. It will become apparent from the discussion that follows, that it is not yet possible to advance an interaction mechanism which can be taken to be completely acceptable. However, there is...

    • THE HIGH TEMPERATURE OXIDATION OF GERMANIUM
      (pp. 383-400)
      J. T. LAW and P. S. MEIGS

      A knowledge of the oxidation rate of germanium at and above room temperature may be of some importance in understanding the effect of an oxide film on the surface properties of germanium itself. It has been shown that at room temperature oxygen has a marked effect on surface conductivity,1 contact potential,2 etc., while long time changes associated with the Brattain-Bardeen2 cycle have been ascribed to the formation and growth of an oxide film. In fact, whenever measurements are made on a surface not deliberately cleaned in vacuum, one is dealing with a germanium-germanium oxide-gas system. One way of understanding the...

    • SHORT CONTRIBUTION: VACUUM MICROBALANCE STUDIES ON SINGLE CRYSTAL GERMANIUM
      (pp. 401-406)
      S. P. WOLSKY and A. B. FOWLER

      The following is a preliminary report on studies made with a quartz microbalance similar in design to those used by Rhodin and Gulbransen.1 The sensitivity of the balance was 0.1 to 0.2 ??g. Buoyancy effects were less than the sensitivity at all pressures used. The balance was enclosed in a mercury pump vacuum system that was capable of pressures of 10-9to 10-10mm. The samples could be heated to 900°C with an external heater that necessarily heated the quartz tube surrounding the sample. Because of the delicacy of the balance, high currents could not be passed through the samples...

  9. SUBJECT INDEX
    (pp. 407-408)
  10. AUTHOR INDEX
    (pp. 409-416)