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Semiconductors
BOOK REVIEWS R. A. SMITH: Semiconductors. Cambridge Uiiversity Press, London, 1959. xvii + 494 pp., 65s.
There follows a chapter on statistics, followed by a lengthy phenomenological treatment of transport phenomena, partly from the approach THE SUBJECTof semiconductor physics has exof the Boltzmann equation, and partly from conpanded, and is expanding, so rapidly that few sideration of the kinetics of the average particle. have dared write a book on this subject that might In the same chapter the major scattering mechanbe out of date by the time of its publication. There isms are discussed. have been, it is true, several accounts of transistor After a short chapter on thermal effects, we electronics and of the more elementary aspects of find a longer one-yet perhaps not long enough, semiconductors. Where these texts have dealt with in view of the great present interest in the subjectthe physics of semiconductor behavior, they have on the optical and magneto-optical properties of been describing material generally regarded as solids. This seems to be the place where it is established by those in the field. The main evident that the writer must either survey the advances in understanding in the past decade material and briefly report the quantum mechanichave been included in a number of review articles ally derived formulae, justifying those parameters that could cover only part of this wide field, and in them that are easily explained, or settle down to were occasionally only marginally committed to a thorough-going explanation with no details an attempt at pedagogical clarity. omitted. The latter approach is not possible here, Of the books available at an intermediate level, granted the original premises for the structure of Dr. SMITH’S effort must rank as one of the best. the book. It is worth noting, however, in passing, It is not, and does not pretend to be, a rigorous that there is no one text at the moment that covers quantum-mechanical treatment of the subject; all of the material of this one at the higher level. none of the recent books known to me are. It is, Although such a well rounded, consistentlyinstead, a very readable account, from a physical written account would be hard to write, it is one point of view, of those topics that have been most of the most needed books in semiconductor investigated in the past few years. Dr. SMITH physics today. To return to the details of the present work, presents his material at a fairly constant level of difficulty, apparently choosing those proofs and the eighth chapter treats at length drift and diffusion theory, followed by a short discussion demonstrations that will most easily persuade his reader. In so doing, he succeeds in avoiding to a of recombination mechanisms and photoconductivity. One recalls that separate texts have large degree the pitfall into which many such texts fall: that of presenting the facile explanation that recently been published on this last topic, so that is really misleading, and requires correction at a the scant treatment of this book is rather summary dismissal. The mechanisms of recombination, as later stage. After several years of teaching semiconductor physics at about this level to graduate distinct from the phenomenology of recombination students at an American university, I can say withcenters and capture cross-sections and the like, out reservation that this book is easily the closest might also feel somewhat slighted by the briefness of their appearance. to a good general text that we have tried. The book opens with a discussion of some After a general chapter on methods of determining semiconductor parameters, Dr. SMITH elementary properties of semiconductors, then passes on to present a review of the behavior of discusses in turn the present status of knowledge of germanium, silicon, diamond and gray tin; electrons moving in periodic potentials. The third selenium, tellurium and boron; the Group III-V chapter discusses the general imperfection in semiconductors, like InSb; Group I-V, II-IV, crystal lattices before particularizing to subII-V semiconductors; the lead “salts”; the CdS stitutional foreign atoms in Group IV and Group III-V semiconductors. The chapter closes with a series; and other more esoteric members of the species. The final chapter deals with the application brief discussion of excitons. 356
BOOK
of semiconductors in rectifiers, transistors, photodetectors, thermoelements, and the like, and runs to some fifty pages out of over four hundred. Dr. SMITH remarks, in his preface, that some subjects had of necessity to be left out of his book. Thus it is easy to justify the absence of much reference to crystal purification techniques and transistor technology. The absence of an adequate discussion of the work on the surface properties of semiconductors and of the low mobility semiconductors extensively studied in the Soviet Union is however regrettable. The tunnel diode is, of course, not treated, simply because, although Esaki’s work was published, its importance had not been recognized at the time the book was written: an example, surely, of the difficulties facing an author in a fast moving field. Another example is the omission of references to the identification of impurity centers using electron spin resonance. The latter criticisms are not important for the immediate usefulness of this book, but will obviously affect its topical&y in a few years time. The treatment of the first ten chapters is such that it may be expected to remain useful for some time to come; the relegation of discussion of the properties of specific semiconductors to the later chapters means that they alone will become out of date. In summary, this reader feels that Semiconductors will prove a most useful text for senior (honour) year and first year graduate students in physics; for those physicists in industry or government who may never have had a formal course in semiconductor physics, or who require a comprehensive review of the subject; and for electronic engineers with some background in elementary quantum mechanics who desire to establish a foundation of knowledge of the physical processes underlying the operation of semiconductor devices. WILLIAM PAUL
W. L. JOLLY: Synthetic Inorganic Chemistry. Prentice-Hall Inc., New Jersey, 1960. 196 pp., $8.00. THIS SHORT book, comprising some sixteen chapters, represents an important contribution to the teaching of inorganic chemistry. The first
REVIEWS
357
five chapters, with their discussions of such subjects as searching the literature and the principles underlying various inorganic reactions, are intended as an introduction to the remainder of the book. Chapter 6 outlines a laboratory course taught to undergraduates at the University of California, while Chapters 7 through 15 describe a series of special experimental techniques, e.g. use of an electric discharge, use of high-pressure apparatus, vacuum manipulation, and the inert atmosphere box. Chapter 16 provides a detailed account of eighteen syntheses designed to emphasize the theoretical principles and laboratory techniques mentioned earlier. In the opinion of this reviewer, Chapters 7 through 15 form the most valuable part of the book, representing the best single source of information on the techniques required for preparing inorganic compounds having some real significance. In a series of clear, concise chapters the author introduces the student to nine special techniques and the ancillary equipment necessary for their use. The value of each of these chapters is still further increased by the inclusion of a useful bibliography designed to lead the reader to more detailed sources of information. Experts will have little justification for advancing any wide criticism of this part of the book, although there are a few places where the text could be improved. Thus in Chapter 10, The Vacuum Line, the stopcocks described are rather more complicated and, therefore, more expensive than necessary, and there are better designs for mercury float valves than those suggested. The publisher described Synthetic Inorganic‘ Chemistry as being both a theoretical and operational text and not merely a cookbook or a book on techniques. These are certainly admirable objectives, but in this reviewer’s opinion an adequate theoretical background is not provided, nor could it be provided in a book of this size. In Chapters 1 through 5 the author has covered too much material too rapidly, so that a student has to refer to other sources of information if he is to obtain anything like a reasonable knowledge of the formation and nature of the substances described later in the book. Chapter 2 in part contains a summary of the thermodynamic and the kinetic considerations involved in synthesis, but the treatment given is at the level of a freshman general chemistry course.
There follows a chapter on statistics, followed by a lengthy phenomenological treatment of transport phenomena, partly from the approach THE SUBJECTof semiconductor physics has exof the Boltzmann equation, and partly from conpanded, and is expanding, so rapidly that few sideration of the kinetics of the average particle. have dared write a book on this subject that might In the same chapter the major scattering mechanbe out of date by the time of its publication. There isms are discussed. have been, it is true, several accounts of transistor After a short chapter on thermal effects, we electronics and of the more elementary aspects of find a longer one-yet perhaps not long enough, semiconductors. Where these texts have dealt with in view of the great present interest in the subjectthe physics of semiconductor behavior, they have on the optical and magneto-optical properties of been describing material generally regarded as solids. This seems to be the place where it is established by those in the field. The main evident that the writer must either survey the advances in understanding in the past decade material and briefly report the quantum mechanichave been included in a number of review articles ally derived formulae, justifying those parameters that could cover only part of this wide field, and in them that are easily explained, or settle down to were occasionally only marginally committed to a thorough-going explanation with no details an attempt at pedagogical clarity. omitted. The latter approach is not possible here, Of the books available at an intermediate level, granted the original premises for the structure of Dr. SMITH’S effort must rank as one of the best. the book. It is worth noting, however, in passing, It is not, and does not pretend to be, a rigorous that there is no one text at the moment that covers quantum-mechanical treatment of the subject; all of the material of this one at the higher level. none of the recent books known to me are. It is, Although such a well rounded, consistentlyinstead, a very readable account, from a physical written account would be hard to write, it is one point of view, of those topics that have been most of the most needed books in semiconductor investigated in the past few years. Dr. SMITH physics today. To return to the details of the present work, presents his material at a fairly constant level of difficulty, apparently choosing those proofs and the eighth chapter treats at length drift and diffusion theory, followed by a short discussion demonstrations that will most easily persuade his reader. In so doing, he succeeds in avoiding to a of recombination mechanisms and photoconductivity. One recalls that separate texts have large degree the pitfall into which many such texts fall: that of presenting the facile explanation that recently been published on this last topic, so that is really misleading, and requires correction at a the scant treatment of this book is rather summary dismissal. The mechanisms of recombination, as later stage. After several years of teaching semiconductor physics at about this level to graduate distinct from the phenomenology of recombination students at an American university, I can say withcenters and capture cross-sections and the like, out reservation that this book is easily the closest might also feel somewhat slighted by the briefness of their appearance. to a good general text that we have tried. The book opens with a discussion of some After a general chapter on methods of determining semiconductor parameters, Dr. SMITH elementary properties of semiconductors, then passes on to present a review of the behavior of discusses in turn the present status of knowledge of germanium, silicon, diamond and gray tin; electrons moving in periodic potentials. The third selenium, tellurium and boron; the Group III-V chapter discusses the general imperfection in semiconductors, like InSb; Group I-V, II-IV, crystal lattices before particularizing to subII-V semiconductors; the lead “salts”; the CdS stitutional foreign atoms in Group IV and Group III-V semiconductors. The chapter closes with a series; and other more esoteric members of the species. The final chapter deals with the application brief discussion of excitons. 356
BOOK
of semiconductors in rectifiers, transistors, photodetectors, thermoelements, and the like, and runs to some fifty pages out of over four hundred. Dr. SMITH remarks, in his preface, that some subjects had of necessity to be left out of his book. Thus it is easy to justify the absence of much reference to crystal purification techniques and transistor technology. The absence of an adequate discussion of the work on the surface properties of semiconductors and of the low mobility semiconductors extensively studied in the Soviet Union is however regrettable. The tunnel diode is, of course, not treated, simply because, although Esaki’s work was published, its importance had not been recognized at the time the book was written: an example, surely, of the difficulties facing an author in a fast moving field. Another example is the omission of references to the identification of impurity centers using electron spin resonance. The latter criticisms are not important for the immediate usefulness of this book, but will obviously affect its topical&y in a few years time. The treatment of the first ten chapters is such that it may be expected to remain useful for some time to come; the relegation of discussion of the properties of specific semiconductors to the later chapters means that they alone will become out of date. In summary, this reader feels that Semiconductors will prove a most useful text for senior (honour) year and first year graduate students in physics; for those physicists in industry or government who may never have had a formal course in semiconductor physics, or who require a comprehensive review of the subject; and for electronic engineers with some background in elementary quantum mechanics who desire to establish a foundation of knowledge of the physical processes underlying the operation of semiconductor devices. WILLIAM PAUL
W. L. JOLLY: Synthetic Inorganic Chemistry. Prentice-Hall Inc., New Jersey, 1960. 196 pp., $8.00. THIS SHORT book, comprising some sixteen chapters, represents an important contribution to the teaching of inorganic chemistry. The first
REVIEWS
357
five chapters, with their discussions of such subjects as searching the literature and the principles underlying various inorganic reactions, are intended as an introduction to the remainder of the book. Chapter 6 outlines a laboratory course taught to undergraduates at the University of California, while Chapters 7 through 15 describe a series of special experimental techniques, e.g. use of an electric discharge, use of high-pressure apparatus, vacuum manipulation, and the inert atmosphere box. Chapter 16 provides a detailed account of eighteen syntheses designed to emphasize the theoretical principles and laboratory techniques mentioned earlier. In the opinion of this reviewer, Chapters 7 through 15 form the most valuable part of the book, representing the best single source of information on the techniques required for preparing inorganic compounds having some real significance. In a series of clear, concise chapters the author introduces the student to nine special techniques and the ancillary equipment necessary for their use. The value of each of these chapters is still further increased by the inclusion of a useful bibliography designed to lead the reader to more detailed sources of information. Experts will have little justification for advancing any wide criticism of this part of the book, although there are a few places where the text could be improved. Thus in Chapter 10, The Vacuum Line, the stopcocks described are rather more complicated and, therefore, more expensive than necessary, and there are better designs for mercury float valves than those suggested. The publisher described Synthetic Inorganic‘ Chemistry as being both a theoretical and operational text and not merely a cookbook or a book on techniques. These are certainly admirable objectives, but in this reviewer’s opinion an adequate theoretical background is not provided, nor could it be provided in a book of this size. In Chapters 1 through 5 the author has covered too much material too rapidly, so that a student has to refer to other sources of information if he is to obtain anything like a reasonable knowledge of the formation and nature of the substances described later in the book. Chapter 2 in part contains a summary of the thermodynamic and the kinetic considerations involved in synthesis, but the treatment given is at the level of a freshman general chemistry course.