Scanning Probe Microscope (SPM) Imaging Modes

Agilent Technologies (Oxford)

Key Features & Specifications

Instrument features

  • Highly modular microscope and scanner
  • Optional Integrated environmental & temperature control
  • Easy fluid operation with open cell
  • Easy sample access with top-down scanning

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Scanning Probe Microscope (SPM) Contact Modes

In Contact Mode AFM, interatomic van der Waals forces become repulsive as the AFM tip comes in close contact with the sample surface. The force exerted between the tip and the sample in contact mode is on the order of about 0.1-1000nN. Under ambient conditions, two other forces besides van der Waals interactions are also generally present. These forces are the capillary force from a thin layer of water in the atmosphere, as well as the mechanical force from the cantilever itself.

Scanning Probe Microscope (SPM) Acoustic AC

Acoustic AC Mode (AAC mode) is an oscillating technique that is less sensitive than MAC Mode, but gentler and less destructive than contact mode. AAC mode excites the cantilever by vibrating the piezo where the cantilever holder is attached. The AAC mode option includes an AAC mode controller and an AAC mode scanner module. AAC mode is included in Agilent MAC Mode.

Scanning Probe Microscope (SPM) MAC Mode

gilent´s patented Magnetic AC Mode (MAC Mode) is a gentle, nondestructive technique for atomic force microscopy that has been designed for imaging extremely delicate samples. MAC Mode allows researchers to image submolecular structures that cannot be resolved with any other AFM technique. It offers the best control available for oscillating probe technology, thereby providing a tremendous benefit for imaging in fluids and imaging soft samples. MAC Mode is particularly useful in areas that require high resolution and force sensitivity especially in a liquid environment, such as biology, polymers, and surface science.

Scanning Probe Microscope (SPM) Phase Imaging

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Phase Imaging is a powerful, dynamic force technique that can reveal many unique mechanical and chemical properties of a sample at the nanometer scale. As the vertically oscillating AFM tip encounters regions of different composition, a change in phase, relative to the phase of the drive signal, is measured and recorded. Phase imaging has been found to be particularly useful for mapping the various components of composite materials, studying variations in the composition and contamination in materials, and measuring adhesion, surface hardness, and elasticity. It has been applied to thin film studies, the materials sciences, and composite characterization.

Scanning Tunneling Microscope (STM)

Scanning Tunneling Microscopy (STM) uses a sharp conducting tip and applies a bias voltage between the tip and the sample. When the tip is brought close to the sample, electrons can “tunnel” through the narrow gap either from the sample to the tip or from the tip to the sample, depending on the sign of the bias voltage. This tunneling current changes with tip-to-sample distance, decaying exponentially as distance increases, thus affording remarkably high precision in positioning the tip (sub-angstrom vertically and atomic resolution laterally). For the electron tunneling to take place, both the sample and the tip must be conductive.

Scanning Probe Microscope (SPM) LFM

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Lateral Force Microscopy (LFM) is useful for studying surfaces that have variations in friction. During contact mode AFM scanning, as the probe is dragged over the surface, changes in surface friction and topographic slope can cause the cantilever to twist and thus create forces on the cantilever that are parallel to the plane of the sample surface. Such lateral forces cause lateral deflection of the cantilever, which is sensed by the photodetector and used to form a lateral force image in a manner similar to a normal AFM deflection image.

Scanning Probe Microscope (SPM) EFM

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Electric Force Microscopy (EFM) measures local electrostatic interaction between a conductive tip and a sample through Coulomb forces. Different areas of the surface may have different responses to the charged tip, depending on their local electrical properties. Variation in electrostatic forces can be detected in the change of oscillation amplitude and phase of the AFM probe. EFM can be utilized in many applications, such as characterizing surface electrical properties, detecting defects of an integrated circuit, and measuring the distribution of a particular material on a composite surface.

Scanning Probe Microscope (SPM) MFM

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Magnetic Force Microscopy (MFM) measures magnetic structures/domains of a surface using a magnetic cantilever. As the magnetic tip scans, the interaction between the tip and the surface is greatly affected by the local magnetic properties. The variations in magnetic forces are measured in acoustic AC mode. MFM is a nondestructive technique that can be used to evaluate magnetic materials and devices or to locate and map magnetic defects on a variety of materials and surfaces.

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Scanning Probe Microscope (SPM) Force Modulation

Force Modulation AFM is a fast, very sensitive imaging method that is especially useful for measuring and detecting variations in a surface’s mechanical properties, including stiffness and elasticity. In this technique, a modulated driving signal at a constant frequency is applied to the AFM cantilever while the AFM tip is in contact with the sample. The amplitude variation and phase lag during the scan are measured. Force modulation has proven its utility in life science studies, polymer studies, experiments on semiconductor materials, and the material sciences.

Scanning Probe Microscope (SPM) Current Sensing

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Current Sensing AFM (CSAFM) uses standard AFM contact mode along with ultrasharp AFM cantilevers coated with a conducting film to simultaneously probe conductivity and topography of a sample. By applying a voltage bias between the substrate and a conducting cantilever, a current flow is generated. This current can be used to construct a spatially resolved conductivity image. CSAFM is useful in molecular recognition studies and can be used to spatially resolve electronic and ionic processes across cell membranes.

Kelvin Force Microscopy (KFM) Imaging Mode

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Kelvin Force Microscopy (KFM) is an atomic force microscopy (AFM) technique in which a conductive AFM tip interacts with the sample according to the sample’s electrostatic characteristics. KFM is an imaging technique that maps the variation of the contact potential between the tip and the sample at each in-plane position. (KFM is also known as surface potential imaging.) Agilent’s MAC Mode III control electronics allows truly-simultaneous recording of topography and KFM images in a single pass, that is, without the time-consuming process of having to scan twice (two-pass scanning), once for topography and once for the electrical image. MAC Mode III enables this by incorporating three independently-controlled lock-in amplifiers, one of which is dedicated to the electrical measurement at the same time that another one is used for topography imaging. This arrangement allows the user to choose the frequencies at which the two lock-in amplifiers operate independently from each other, increasing the operational freedom for electrical experiments. The simultaneous measurement scheme, obviating the need for two-pass scanning, also eliminates the adverse effects on the fidelity of the electrical image that come about due to the drift that the scanner may suffer during the second pass of a two-pass implementation.

Agilent Scanning Microwave Microscopy (SMM) Mode

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Agilent’s unique scanning microwave microscopy (SMM) mode combines the comprehensive electrical measurement capabilities of a performance network analyzer (PNA) with the outstanding spatial resolution of an atomic force microscope. SMM Mode outperforms traditional AFM-based scanning capacitance microscopy techniques, offering far greater application versatility, the ability to acquire quantitative results, and the highest sensitivity and dynamic range in the industry.

The ability to provide calibrated, high-sensitivity, complex electrical and spatial measurements makes SMM Mode particularly useful for semiconductor test and characterization. As well as working on semiconductors, glasses, polymers, ceramics, and metals, SMM Mode lets Agilent 5400 and 5600LS users perform high-sensitivity investigations of ferroelectric, dielectric, and PZT materials. Studies of organic films, membranes, and biological samples can also benefit from SMM Mode. Its very high sensitivity (1.2aF) is ideal for looking at ion channels.

Features and Benefits

  • Provides exceptionally high spatial and electrical resolution
  • Offers highest sensitivity and dynamic range in the industry
  • Enables complex impedance (resistance and reactance), calibrated capacitance, calibrated dopant density, and topography measurements
  • Works on all semiconductors: Si, Ge, III-V, and II-VI
  • Operates at multiple frequencies (variable up to 6GHz)
  • Does not require an oxide layer

Description

The Agilent 5500 AFM/SPM microscope offers numerous unique features, such as patented top-down scanning and unrivalled environmental and temperature control, while providing maximum flexibility and modularity. The universal microscope base permits easy integration with an environmental chamber or an inverted optical microscope. Sample preparation is made easy with our unique sample plates designed for your application including imaging in fluids.

A top-down optical axis through the scanner allows an unobstructed view of the cantilever and the sample without sacrificing sample handling. The scanner’s modular nose cone makes changing imaging modes quick and easy. The Agilent 5500 SPM/AFM is a high performance system that facilitates advanced applications solutions. It offers atomic resolution and is ideal for electrochemistry, polymers, and soft material applications.

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