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Scanning tunneling microscopy and spectroscopy: Theory, techniques and applications
Pergamon
Materials Research Bulletin, Vol. 29, No. 7, pp. 811-813, t994 Copyright © 1994 Elsevier Science Ltd lh-inted in the USA. All rights reserved 0025-5408/94 $6.00 + .00
BOOK REVIEWS
INTRODUCTION TO SCANNING TUNNELING MICROSCOPY, by C. Julian Chen. Oxford Series in Optical and Imaging Sciences 4, Oxford U n i v e r s i t y Press, New York/Oxford (1993), 412 pp. Price: $65.00. ISBN 0-19-507150-6 ( c l o t h ) . and SCANNING TUNNELING MICROSCOPY AND SPECTROSCOPY: THEORY, TECHNIQUES AND APPLICATIONS, edited by Dawn A. Bonnell. VCH Publishers, New York (1993), 436 pp. Price: $125.00. ISBN 0-89573-768-X ( c l o t h ) . The l a s t decade has witnessed an explosive growth in the use of scanning tunneling microscopy (STM) and related techniques, to the point where they have become routine tools f o r surface c h a r a c t e r i z a t i o n . This rapid progress has outstripped the production of introductory t e x t s , with the r e s u l t that i n i t i a t e s and students face the prospect of sorting through more than a thousand papers published in t h i s area with only the assistance of review a r t i c l e s , which are often not pitched at a suitable pedagogical l e v e l . Julian Chen has d e l i b e r a t e l y set out to f i l l t h i s void by producing a r e f e r e n c e / t e x t book that concentrates on the deliberate development of the fundamental physics of STM and scanning tunneling spectroscopy (STS). He also provides a wealth of d e t a i l on instrumentation issues, but spends l i t t l e time on applications and a n c i l l a r y techniques. A f t e r an overview chapter (50 pages) that in i t s e l f may be s u f f i c i e n t f o r an undergraduate or casual reader, the book is divided into two roughly equal parts that cover, f i r s t , imaging mechanisms and then instrumentation and a p p l i cations. A number of Appendices provide background material on topics as d i verse as Green's functions and operational a m p l i f i e r s . Part I pursues a time-dependent perturbation theory approach (based on the work of Bardeen) to tunneling and image formation. The development is det a i l e d , but c l e a r , and includes consideration of the e f f e c t of t i p - s u r f a c e forces on tunneling and mechanical tip-sample e f f e c t s . As he has argued in his published work, Chen promotes the idea that 1>0 angular momentum components of the t i p wavefunction may play a s i g n i f i c a n t role in STM images in some cases. The bulk of Part I I covers the physical p r i n c i p l e s underlying STM i n s t r u mentation, including p i e z o e l e c t r i c scanners, v i b r a t i o n i s o l a t i o n , e l e c t r o n i c s , coarse positioning ( l i c e , inchworms, e t c . ) and t i p treatment. The level of discussion is often s u r p r i s i n g l y detailed and p r a c t i c a l l y useful; f o r instance, the chapter on piezo devices includes a section on i n - s i t u t e s t i n g and c a l i b r a t i o n . Applications from a v a r i e t y of areas are dealt with in a purely i l l u s t r a t i v e way in a mere 20 pages. 811
812
BOOK REVIEWS
Vol. 29, No. 7
A comprehensive l i s t of references is provided, and the index is adequate. For those with an i n t e r e s t in the h i s t o r y of the technique, a " g a l l e r y " o f w e l l known STM images ( p r i m a r i l y of semiconductors) is reproduced, together with a photograph of the o r i g i n a l device of Binnig and Rohrer, who are also seen in a picture of the IBM ZUrich soccer team taken on the day of the announcement of t h e i r Nobel prize. Who could b e n e f i t from t h i s book? I t c e r t a i n l y uses a textbook approach that is unique in the STM l i t e r a t u r e . On the other hand, i t is too detailed to be a r e a l i s t i c textbook, unless one is teaching a high-level course s p e c i f i c a l l y dedicated to STM. The careful t h e o r e t i c a l development and d e t a i l on i n s t r u mentation makes t h i s book i d e a l l y suited as a reference f o r the well-prepared graduate student s t a r t i n g a research project in t h i s area. As such, t h i s v o l ume is l i k e l y to find a place in many laboratory bookcases. The volume edited by Dawn Bonnell makes no pretensions to be a textbook, but rather is intended to be "a bridge between monographs or review type coverages and the potential STM/AFM e x p e r i m e n t a l i s t . " She has recruited many of the major names in the f i e l d as authors, but the level generally remains appropriate f o r an upper-level undergraduate or a beginning graduate student. The treatment of fundamental concepts is b r i e f , and much space is devoted to reviews of applications and techniques related to STM. The f i r s t quarter of the book includes a b r i e f discussion of microscope design and operation (Bonnell), and e x c e l l e n t chapters on the theory of STM (Tersoff) and tunneling spectroscopy (Hamers). Part I I covers the structure of sample and t i p surfaces in two chapters. The f i r s t is a substantial (50 pages) review of surface structure by Unertl, with l i t t l e d i r e c t reference to STM. This is in i t s e l f a good exposition but, given the lack of other background material in the book, t h i s chapter seems out of place. In the second chapter, Rohrer gives detailed explanations of how to prepare STM t i p s and methods of sample surface preparation. Part I I I occupies roughly h a l f of t h i s volume, and includes chapters on force microscopy (Colton and Burnham), b a l l i s t i c electron emission spectroscopy (Kaiser et a l . ) , and electrochemical (Bard and Fan) and b i o l o g i c a l (Lindsay) applications of STM. These chapters are of uniformly high q u a l i t y and are copiously referenced. In an appendix is a l i s t i n g of a FORTRAN program f o r the c a l c u l a t i o n of tunneling current (by Clayton Teague of NIST). Apparently, t h i s program was used to calculate "the data f o r graphs and tables given in Part l l . " As there do not appear to be any such graphs and table in Part I I that could have been derived from t h i s program, i t is not at a l l clear j u s t what i t was used f o r , but some readers may f i n d i t of use. I t is d i f f i c u l t to regard t h i s book as much more than a c o l l e c t i o n of review material that has appeared elsewhere, despite the claims in the introduct i o n . But, having said t h i s , these are very good reviews by experts in t h e i r respective f i e l d s and they are here collected in one place. This volume would serve as an e x c e l l e n t wide-ranging introduction f o r new students and s c i e n t i s t s wanting to come up to speed in STM and related techniques. These two volumes are a contrast in s t y l e and content. Chen's exposition is detailed and pedagogical ina uniform s t y l e . I t provides a wealth of r e f e r ence material about the fundamental physics and instrumentation, but l i t t l e about a p p l i c a t i o n s . Bonnell's e d i t i o n , by i t s nature, is less u n i f i e d and has less d e t a i l concerning fundamentals, but oresents an e x c e l l e n t overview of important a p p l i c a t i o n areas and related techniques. I f you are looking f o r a reference f o r students in the laboratory, then Chen's book is an e x c e l l e n t buy. I f you need w e l l - w r i t t e n reviews (circa 1992) that cover a wide range of STMrelated topics, then the volume edited by Bonnell may save a l o t of digging in the l i b r a r y , but be prepared to dig deep in your pocket f o r the p r i v i l e g e . Reviewed by P.R. Watson, Department of Chemistry, Oregon State U n i v e r s i t y .
Materials Research Bulletin, Vol. 29, No. 7, pp. 811-813, t994 Copyright © 1994 Elsevier Science Ltd lh-inted in the USA. All rights reserved 0025-5408/94 $6.00 + .00
BOOK REVIEWS
INTRODUCTION TO SCANNING TUNNELING MICROSCOPY, by C. Julian Chen. Oxford Series in Optical and Imaging Sciences 4, Oxford U n i v e r s i t y Press, New York/Oxford (1993), 412 pp. Price: $65.00. ISBN 0-19-507150-6 ( c l o t h ) . and SCANNING TUNNELING MICROSCOPY AND SPECTROSCOPY: THEORY, TECHNIQUES AND APPLICATIONS, edited by Dawn A. Bonnell. VCH Publishers, New York (1993), 436 pp. Price: $125.00. ISBN 0-89573-768-X ( c l o t h ) . The l a s t decade has witnessed an explosive growth in the use of scanning tunneling microscopy (STM) and related techniques, to the point where they have become routine tools f o r surface c h a r a c t e r i z a t i o n . This rapid progress has outstripped the production of introductory t e x t s , with the r e s u l t that i n i t i a t e s and students face the prospect of sorting through more than a thousand papers published in t h i s area with only the assistance of review a r t i c l e s , which are often not pitched at a suitable pedagogical l e v e l . Julian Chen has d e l i b e r a t e l y set out to f i l l t h i s void by producing a r e f e r e n c e / t e x t book that concentrates on the deliberate development of the fundamental physics of STM and scanning tunneling spectroscopy (STS). He also provides a wealth of d e t a i l on instrumentation issues, but spends l i t t l e time on applications and a n c i l l a r y techniques. A f t e r an overview chapter (50 pages) that in i t s e l f may be s u f f i c i e n t f o r an undergraduate or casual reader, the book is divided into two roughly equal parts that cover, f i r s t , imaging mechanisms and then instrumentation and a p p l i cations. A number of Appendices provide background material on topics as d i verse as Green's functions and operational a m p l i f i e r s . Part I pursues a time-dependent perturbation theory approach (based on the work of Bardeen) to tunneling and image formation. The development is det a i l e d , but c l e a r , and includes consideration of the e f f e c t of t i p - s u r f a c e forces on tunneling and mechanical tip-sample e f f e c t s . As he has argued in his published work, Chen promotes the idea that 1>0 angular momentum components of the t i p wavefunction may play a s i g n i f i c a n t role in STM images in some cases. The bulk of Part I I covers the physical p r i n c i p l e s underlying STM i n s t r u mentation, including p i e z o e l e c t r i c scanners, v i b r a t i o n i s o l a t i o n , e l e c t r o n i c s , coarse positioning ( l i c e , inchworms, e t c . ) and t i p treatment. The level of discussion is often s u r p r i s i n g l y detailed and p r a c t i c a l l y useful; f o r instance, the chapter on piezo devices includes a section on i n - s i t u t e s t i n g and c a l i b r a t i o n . Applications from a v a r i e t y of areas are dealt with in a purely i l l u s t r a t i v e way in a mere 20 pages. 811
812
BOOK REVIEWS
Vol. 29, No. 7
A comprehensive l i s t of references is provided, and the index is adequate. For those with an i n t e r e s t in the h i s t o r y of the technique, a " g a l l e r y " o f w e l l known STM images ( p r i m a r i l y of semiconductors) is reproduced, together with a photograph of the o r i g i n a l device of Binnig and Rohrer, who are also seen in a picture of the IBM ZUrich soccer team taken on the day of the announcement of t h e i r Nobel prize. Who could b e n e f i t from t h i s book? I t c e r t a i n l y uses a textbook approach that is unique in the STM l i t e r a t u r e . On the other hand, i t is too detailed to be a r e a l i s t i c textbook, unless one is teaching a high-level course s p e c i f i c a l l y dedicated to STM. The careful t h e o r e t i c a l development and d e t a i l on i n s t r u mentation makes t h i s book i d e a l l y suited as a reference f o r the well-prepared graduate student s t a r t i n g a research project in t h i s area. As such, t h i s v o l ume is l i k e l y to find a place in many laboratory bookcases. The volume edited by Dawn Bonnell makes no pretensions to be a textbook, but rather is intended to be "a bridge between monographs or review type coverages and the potential STM/AFM e x p e r i m e n t a l i s t . " She has recruited many of the major names in the f i e l d as authors, but the level generally remains appropriate f o r an upper-level undergraduate or a beginning graduate student. The treatment of fundamental concepts is b r i e f , and much space is devoted to reviews of applications and techniques related to STM. The f i r s t quarter of the book includes a b r i e f discussion of microscope design and operation (Bonnell), and e x c e l l e n t chapters on the theory of STM (Tersoff) and tunneling spectroscopy (Hamers). Part I I covers the structure of sample and t i p surfaces in two chapters. The f i r s t is a substantial (50 pages) review of surface structure by Unertl, with l i t t l e d i r e c t reference to STM. This is in i t s e l f a good exposition but, given the lack of other background material in the book, t h i s chapter seems out of place. In the second chapter, Rohrer gives detailed explanations of how to prepare STM t i p s and methods of sample surface preparation. Part I I I occupies roughly h a l f of t h i s volume, and includes chapters on force microscopy (Colton and Burnham), b a l l i s t i c electron emission spectroscopy (Kaiser et a l . ) , and electrochemical (Bard and Fan) and b i o l o g i c a l (Lindsay) applications of STM. These chapters are of uniformly high q u a l i t y and are copiously referenced. In an appendix is a l i s t i n g of a FORTRAN program f o r the c a l c u l a t i o n of tunneling current (by Clayton Teague of NIST). Apparently, t h i s program was used to calculate "the data f o r graphs and tables given in Part l l . " As there do not appear to be any such graphs and table in Part I I that could have been derived from t h i s program, i t is not at a l l clear j u s t what i t was used f o r , but some readers may f i n d i t of use. I t is d i f f i c u l t to regard t h i s book as much more than a c o l l e c t i o n of review material that has appeared elsewhere, despite the claims in the introduct i o n . But, having said t h i s , these are very good reviews by experts in t h e i r respective f i e l d s and they are here collected in one place. This volume would serve as an e x c e l l e n t wide-ranging introduction f o r new students and s c i e n t i s t s wanting to come up to speed in STM and related techniques. These two volumes are a contrast in s t y l e and content. Chen's exposition is detailed and pedagogical ina uniform s t y l e . I t provides a wealth of r e f e r ence material about the fundamental physics and instrumentation, but l i t t l e about a p p l i c a t i o n s . Bonnell's e d i t i o n , by i t s nature, is less u n i f i e d and has less d e t a i l concerning fundamentals, but oresents an e x c e l l e n t overview of important a p p l i c a t i o n areas and related techniques. I f you are looking f o r a reference f o r students in the laboratory, then Chen's book is an e x c e l l e n t buy. I f you need w e l l - w r i t t e n reviews (circa 1992) that cover a wide range of STMrelated topics, then the volume edited by Bonnell may save a l o t of digging in the l i b r a r y , but be prepared to dig deep in your pocket f o r the p r i v i l e g e . Reviewed by P.R. Watson, Department of Chemistry, Oregon State U n i v e r s i t y .