Anal. Chem. 1998, 70, 425R-475R
Scanning Probe Microscopy Lawrence A. Bottomley
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400 Review Contents
Table 1. List of Acronyms
Technical Advances in SPM Books and Reviews Instrumentation Tips and Cantilevers Calibration and Metrology Theory New Probe Techniques Magnetic Resonance Force Microscopy Magnetic Force Microscopy Ballistic Electron Emission Microscopy Near-Field Scanning Optical Microscopy Microcantilever Sensors Force Measurements Nanoindentation Biological Applications of Force Sensing Imaging Applications Electrochemical Scanning Probe Microscopy Self-Assembled Monolayers Langmuir-Blodgett Films Biomolecules Polymers Materials Semiconductors Crystal Growth Nanotechnology Nanoparticles and Nanoclusters Break Junctions and Conductance Quantization Nanolithography Nanofabrication Literature Cited
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Scanning probe microscopy encompasses a family of techniques that provide measurement of surface topography and surface properties on the atomic scale. Since its inception in 1982, the number of papers devoted to technical advances and applications of SPM (see Table 1 for a list of acronyms) has risen at a dramatic rate. Contributing factors include the availability of highquality commercial instrumentation, the wide range of conditions under which high-resolution measurements can be made (in a vacuum, liquid, and gas from 4 to over 700 K), and the renewed focus among scientists and engineers to gain insights into molecular interactions and to manipulate matter on the atomic scale. This review covers papers published during the period October 1, 1995 through October 31, 1997. Because of the sheer number of publications (5450) and the space available in the journal, this review cannot be all inclusive. The articles cited illustrate only some of the research avenues currently being explored with SPM. The citations in this review were downloaded from the STN International Data Base. Author claims were paraphrased from the abstracts without consideration of their scientific validity. S0003-2700(98)00011-0 CCC: $15.00 Published on Web 05/19/1998
© 1998 American Chemical Society
BEEM BEES CVD DNA ECSFM ECSPM ECSTM FFM FMM HOPG IRAS LB LFM MFM MOCVD MOKE MOS MRFM NSOM PSTM RNA SAM SCM SECM SEM SFM SIMS SPM SThM STM STS TEM TM UPD UHV VLSI
ballistic electron emission microscopy ballistic electron emission spectroscopy chemical vapor deposition deoxyribonucleic acid electrochemical scanning force microscopy/ microscope electrochemical scanning probe microscopy/ microscope electrochemical scanning tunneling microscopy/ microscope friction force microscopy/microscope force modulation microscopy/microscope highly oriented pyrolytic graphite infrared reflection absorption spectroscopy Langmuir-Blodgett lateral force microscopy/microscope magnetic force microscopy/microscope metal organic chemical vapor deposition magnetooptic Kerr effect metal-oxide-semiconductor magnetic resonance force microscopy/ microscope near-field scanning optical microscopy/ microscope photon scanning tunneling microscopy/ microscope ribonucleic acid self-assembled monolayer scanning capacitance microscopy/microscope scanning electrochemical microscopy/microscope scanning electron microscopy/microscope scanning force microscopy/microscope secondary ion mass spectrometry scanning probe microscopy/microscope scanning thermal microscopy/microscope scanning tunneling microscopy/microscope scanning tunneling spectroscopy transmission electron microscopy/microscope tapping mode underpotential deposition ultrahigh vacuum very large scale integration
TECHNICAL ADVANCES IN SPM Books and Reviews. Wiesendanger and Guentherodt (A1) have edited a series of books on STM. The theme of the third volume was theory of STM and related scanning probe methods. Several reviews concerning the theory and practice of proximal probe techniques were published during the past two years (A2A5). Castle and Zhdan (A6) reviewed the problems and solutions provided by SEM and SFM in the characterization of surface topography. Sautet (A7) reviewed pitfalls and difficulties of imaging adsorbates with STM. Several reviews focused on the characterization of clean metal surfaces with STM (A8-A13). Kitazawa (A14) reviewed STS on high-temperature superconductors. Murray and co-workers (A15) reviewed reactions between different chemical species on singlecrystal metal surfaces. STM gives unique insight at the atomic level into the mechanistic details of surface reactions, decomposition of molecules, and influence of defect sites on reactivity. Analytical Chemistry, Vol. 70, No. 12, June 15, 1998 425R
Chiang (A16) critically reviewed the application of UHV-STM to the study of molecular binding site, coverage, overlayer structure, diffusion, and chemical reactivity of small adsorbed molecules on metal surfaces. Hamers et al. (A17) reviewed atomically resolved investigations of surface reaction chemistry by STM, particularly emphasizing semiconductor surface chemistry, adsorption processes at metals, and in situ studies of dissolution and redox chemistry of minerals. Lieber and coworkers (A18) reviewed the utility of SPM techniques combined with wet chemical methods for advancing our understanding of charge density waves, high-temperature superconductors, and nanofabrication in low-dimensional materials. Tirrell (A19) reviewed force measurements between layers of amphiphiles, polyelectrolytes, and biomolecules. Emphasis was placed on measurement of structural forces and forces of specific intermolecular interaction or recognition with SFM. Zasadzinski (A20) reviewed new ways to generate image contrast in SFM. Special emphasis was placed on friction and adhesion force mapping of local surface chemical or biological activity. Pierres and co-workers (A21) reviewed the application of force measurements between surface-associated molecules. Special emphasis is placed on the formation and dissociation of individual molecular bonds between receptor-bearing cells or particles and ligandderivatized surfaces. Allen et al. (A22) reviewed the use of SFM in analytical biotechnology, placing particular emphasis on the measurement of forces between surfaces and how the instrument can be used to directly probe biomolecular interactions. Khan and Sheetz (A23) reviewed the effect of force on biochemical kinetics. With SFM and laser tweezers, measurement of forces at the single-molecule level can be accomplished and provide a means for determining how force is transduced into a change in enzyme activity. Ikai (A24) reviewed the application of STM and SFM to bioorganic molecules and structures. Special emphasis was placed on approaches that are expected to contribute to the creation of a new field of “single-molecule biochemistry”. Manne and Gaub (A25) published a critical review of force microscopy and its utility in the measurement of local interfacial forces and surface stresses. Kruger and co-workers (A26) reviewed the physical properties of dynamic force microscopies in contact and noncontact operation. Frommer (A27) reviewed the application of SPM to organic materials for successful and noninvasive imaging of soft samples. Emphasis was placed on SPM measurements of adhesion, elasticity, friction, and quantification of individual bonding interactions. Durig and Stalder (A28) reviewed the role of proximal probe techniques in characterizing adhesion on the nanometer scale. Carpick and Salmeron (A29) reviewed fundamental investigations of tribology with SFM. Gilicinski et al. (A30) reviewed the applications of SFM in the adhesives industry. Noy and co-workers (A31) presented an in-depth review of chemical force microscopy and its application to probe the strength of individual molecular interactions. Friedbacher et al. (A32) reviewed the background, principles, and analytical potential of SFM and provided selected examples and applications including characterization of aerosol particles and in-situ studies of thinfilm deposition and of glass corrosion. Freeman and Nunes (A33) reviewed recent work on combinations of SPM and ultrafast laser techniques. In the case of repetitive phenomena, stroboscopic 426R
Analytical Chemistry, Vol. 70, No. 12, June 15, 1998
approaches applied to scanned probes yield simultaneous high temporal and spatial resolution. Additional reviews targeting specific applications are cited below in appropriate subsections. Instrumentation. STM. Improvements in STM instrumentation have centered around measurement of tunneling transients, ultrafast scanning, tunneling over wide ranges in temperature (B1, B2), and coupling the tunneling microscope with spectroscopic instruments for chemical identification. Keil and co-workers (B3) observed a transient signal with 2.9-ps pulse width in tunneling mode and 5 ps in contact mode using a fiber-coupled ultrafast STM with a photoconductive gate in the tunneling current circuit. Curtis and co-workers (B4) imaged a Si(111) surface at a tip scan speed of e8000 nm/s while maintaining atomic resolution. Ukraintsev and Yates (B5) used nanosecond laser pulses to initiate a transient increase in tunneling current between a W tip and a Si surface in their UHV instrument. As the laser power was increased, single-atom transfer from the tip to a silicon surface occurred. The number of atoms transferred was controlled by the laser flux. The transfer process was virtually independent of the tip-sample bias polarity. Krieger et al. (B6) described experiments involving the generation of nonlinear current components by laser radiation in the STM tunneling junction. IR radiation rectification and difference-frequency generation were observed. Tsuji and Wagatsuma (B7) irradiated a sample surface with X-rays and recorded an increase in tunneling current between the tip and the sample. This current, originating from electron emission from the sample surface, can be used for surface analysis. The STM tip current was amplified by gaseous molecules in the gap (B8). Spence and co-workers (B9) chemically identified clusters of atoms from identifiable sites on an extended crystal surface by transfer of the clusters to the STM tip and subsequent injection into a time-of-flight mass spectrometer. Van Patten and coworkers (B10) modified the STM so that the bias voltage also serves as an excitation source for arc atomic emission spectroscopy. This so-called “spark-gap atomic emission microscope” allowed unambiguous elemental analytical of species present on the surface. The present instrument is capable of ∼1 µm2 spatial resolution and an absolute detection limit for Cu of
