scholarly journals False Engagements in AFM

1999 ◽  
Vol 7 (2) ◽  
pp. 26-27
Author(s):  
Chetan Dandavate
Keyword(s):  
Laser Beam ◽  
Atomic Force Microscope ◽  
Contact Force ◽  
Feedback Circuit ◽  
Contact Mode ◽  
Voltage Difference ◽  
Atomic Force ◽  
Photo Detectors

In scanning microscopes, like the Atomic Force Microscope (AFM), used in contact mode, scanning begins with engaging the tip with the sample at some contact force, which can be adjusted by the setpoint* (this is common to Digital Instruments' AFMs). It may differ for other brands. For a system that detects the motion of the cantilever with a laser beam, the setpoint basically gives an idea of the voltage difference between the top and bottom photo detectors, When the tip comes into contact, the feedback circuit adjusts the tip deflection according to the required contact force, This is the method commonly followed for the constant deflection method.

The atomic-force microscope and its future in biology

1993 ◽  
Vol 51 ◽  
pp. 704-705
Author(s):  
Jean-Paul Revel
Keyword(s):  
Silicon Nitride ◽  
Laser Beam ◽  
Atomic Force Microscope ◽  
Scanning Tunneling Microscope ◽  
Point Of View ◽  
Scanning Tunneling ◽  
Close Relative ◽  
Tunneling Microscope ◽  
Atomic Force ◽  
Sharp Point

The last few years have been marked by a series of remarkable developments in microscopy. Perhaps the most amazing of these is the growth of microscopies which use devices where the place of the lens has been taken by probes, which record information about the sample and display it in a spatial from the point of view of the context. From the point of view of the biologist one of the most promising of these microscopies without lenses is the scanned force microscope, aka atomic force microscope.This instrument was invented by Binnig, Quate and Gerber and is a close relative of the scanning tunneling microscope. Today's AFMs consist of a cantilever which bears a sharp point at its end. Often this is a silicon nitride pyramid, but there are many variations, the object of which is to make the tip sharper. A laser beam is directed at the back of the cantilever and is reflected into a split, or quadrant photodiode.

A Study of the Photoelectric Effect Caused by a Laser Beam Used in a Beam Bounce Technique in a C-AFM System

2008 ◽  
Author(s):  
Hung-Sung Lin ◽  
Mong-Sheng Wu
Keyword(s):  
Laser Beam ◽  
Failure Analysis ◽  
Atomic Force Microscope ◽  
Photoelectric Effect ◽  
Scanning Probe ◽  
Nanometer Scale ◽  
Electrical Characteristics ◽  
Atomic Force ◽  
Probe Microscope ◽  
Probe Head

Abstract The use of a scanning probe microscope (SPM), such as a conductive atomic force microscope (C-AFM) has been widely reported as a method of failure analysis in nanometer scale science and technology [1-6]. A beam bounce technique is usually used to enable the probe head to measure extremely small movements of the cantilever as it is moved across the surface of the sample. However, the laser beam used for a beam bounce also gives rise to the photoelectric effect while we are measuring the electrical characteristics of a device, such as a pn junction. In this paper, the photocurrent for a device caused by photon illumination was quantitatively evaluated. In addition, this paper also presents an example of an application of the C-AFM as a tool for the failure analysis of trap defects by taking advantage of the photoelectric effect.

scholarly journals Redesigned Sensor Holder for an Atomic Force Microscope with an Adjustable Probe Direction

2021 ◽  
Author(s):  
Janik Schaude ◽  
Maxim Fimushkin ◽  
Tino Hausotte
Keyword(s):  
Atomic Force Microscope ◽  
Piezoelectric Actuator ◽  
High Speed ◽  
Closed Loop ◽  
Coefficient Of Thermal Expansion ◽  
Measuring System ◽  
Contact Mode ◽  
Loop Control ◽  
Atomic Force ◽  
Measuring Machine

AbstractThe article presents a redesigned sensor holder for an atomic force microscope (AFM) with an adjustable probe direction, which is integrated into a nano measuring machine (NMM-1). The AFM, consisting of a commercial piezoresistive cantilever operated in closed-loop intermitted contact-mode, is based on two rotational axes, which enable the adjustment of the probe direction to cover a complete hemisphere. The axes greatly enlarge the metrology frame of the measuring system by materials with a comparatively high coefficient of thermal expansion. The AFM is therefore operated within a thermostating housing with a long-term temperature stability of 17 mK. The sensor holder, connecting the rotational axes and the cantilever, inserted one adhesive bond, a soldered connection and a geometrically undefined clamping into the metrology circle, which might also be a source of measurement error. It has therefore been redesigned to a clamped senor holder, which is presented, evaluated and compared to the previous glued sensor holder within this paper. As will be shown, there are no significant differences between the two sensor holders. This leads to the conclusion, that the three aforementioned connections do not deteriorate the measurement precision, significantly. As only a minor portion of the positioning range of the piezoelectric actuator is needed to stimulate the cantilever near its resonance frequency, a high-speed closed-loop control that keeps the cantilever within its operating range using this piezoelectric actuator further on as actuator was implemented and is presented within this article.

scholarly journals Design and Fabrication of a High-Speed Atomic Force Microscope Scan-Head

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 362
Author(s):  
Luke Oduor Otieno ◽  
Bernard Ouma Alunda ◽  
Jaehyun Kim ◽  
Yong Joong Lee
Keyword(s):  
Atomic Force Microscope ◽  
Natural Frequency ◽  
High Speed ◽  
Contact Mode ◽  
Ongoing Process ◽  
Atomic Force ◽  
Constant Height ◽  
Mode Tracking

A high-speed atomic force microscope (HS-AFM) requires a specialized set of hardware and software and therefore improving video-rate HS-AFMs for general applications is an ongoing process. To improve the imaging rate of an AFM, all components have to be carefully redesigned since the slowest component determines the overall bandwidth of the instrument. In this work, we present a design of a compact HS-AFM scan-head featuring minimal loading on the Z-scanner. Using a custom-programmed controller and a high-speed lateral scanner, we demonstrate its working by obtaining topographic images of Blu-ray disk data tracks in contact- and tapping-modes. Images acquired using a contact-mode cantilever with a natural frequency of 60 kHz in constant deflection mode show good tracking of topography at 400 Hz. In constant height mode, tracking of topography is demonstrated at rates up to 1.9 kHz for the scan size of 1μm×1μm with 100×100 pixels.

Manipulation of Nickel Nanoparticles Deposited on HOPG

2004 ◽  
Vol 853 ◽  
Author(s):  
Massood Z. Atashbar ◽  
Valery N. Bliznyuk ◽  
Srikanth Singamaneni
Keyword(s):  
Atomic Force Microscope ◽  
Magnetic Force ◽  
Nickel Nanoparticles ◽  
Pyrolytic Graphite ◽  
Critical Force ◽  
Contact Mode ◽  
Cyclic Voltametry ◽  
Atomic Force ◽  
Nickel Nanowires ◽  
Plating Solution

ABSTRACTNickel nanowires were fabricated by electrodepositing Ni from an aqueous plating solution onto the step edges of Highly Oriented Pyrolytic Graphite (HOPG). Freshly cleaved HOPG was exposed to a plating solution of nickel and electro chemically deposited by cyclic voltametry. The morphology of the deposited nanoparticles was studied using an Atomic Force Microscope (AFM) in non-contact mode. The magnetic force of interaction between the nanoparticles was studied by magnetizing the particles. The critical force to displace the nanoparticles was estimated using contact mode of AFM.

Atomic Paths in Scanning of the AFM Tip above the Close-Packed Surface in Repulsive Mode

1998 ◽  
Vol 05 (05) ◽  
pp. 989-996
Author(s):  
E. V. Blagov ◽  
G. L. Klimchitskaya ◽  
V. M. Mostepanenko
Keyword(s):  
Atomic Force Microscope ◽  
Vertical Resolution ◽  
Contact Mode ◽  
Atomic Force ◽  
Elastic Approximation

The paths are calculated for the surface and tip apex atoms when scanning the AFM tip above the close-packed lattice in contact mode. The interaction of the sample and the tip atoms is considered in elastic approximation. The dependence of the atomic paths on the type of the tip and its orientation is investigated. It is shown that the vertical characteristic sizes of the atomic paths are several times larger than the vertical resolution of the atomic force microscope.

Modeling the Thermomechanical Interaction Between an Atomic Force Microscope Cantilever and Laser Light

2012 ◽  
Author(s):  
Aarti Chigullapalli ◽  
Jason V. Clark
Keyword(s):  
Laser Beam ◽  
Resonance Frequency ◽  
Atomic Force Microscope ◽  
Laser Power ◽  
Laser Light ◽  
Laser Spot ◽  
Design Parameters ◽  
Atomic Force ◽  
Voltage Signal ◽  
Afm Cantilever

In this paper, we present the first computational model of the thermomechanical interaction between an atomic force microscope (AFM) cantilever and laser light. We validate simulation with experiment. Design parameters of our model include AFM laser power, laser spot position, and geometric and material properties of the cantilever. In the area of nanotechnology, the laser beam deflection method has been widely used in AFMs for detecting the cantilever’s deflection and resonance frequency. The laser deflection method consists of reflecting a laser beam off of an AFM cantilever onto a photo diode, which is converted to a voltage signal. Deflection of the cantilever results in a change in the laser reflection angle and a change in voltage signal. The mechanical properties of the cantilever affect the amount of deflection. Although much work has been done on increasing the sensitivity of the AFM, little work has been done on investigating the thermal effect of the laser-cantilever interaction. We observe that laser-induced thermal expansions in the AFM cantilever are measureable. Our simulated results suggest that both the laser power and spot positions significantly change the resonant response of the cantilevers. The resonance response is critical for the AFM tapping mode. In considering various laser powers, we observe that as we increase the power, the average temperature of the beam increases, which causes a decrease in resonance frequency. In considering various laser reflection spot positions, we find that as the laser spot moves away from the clamped end of the cantilever, the dissipation to the sample which is 6 m below the cantilever tip decreases, causing an increase in temperature but decrease in material softening. The results of our models are close to the experimental results with a relative error of 0.1%.

Nano-Contact Force Calculation Method of Different Tip Radius of Curvature and the Specimen Surface of AFM

2015 ◽  
Vol 723 ◽  
pp. 952-957
Author(s):  
Guo Dong Cheng ◽  
Xiao Jing Yang
Keyword(s):  
Atomic Force Microscope ◽  
Contact Force ◽  
Calculation Model ◽  
Specimen Surface ◽  
Radius Of Curvature ◽  
Force Model ◽  
Atomic Force ◽  
Working Principle ◽  
Tip Radius ◽  
Force Calculation

Atomic Force Microscope (AFM) works by the force between the probe tip and specimen surface. The nanocontact force between the probe tip and specimen surface has an important influence on the detection surface. Base on the analysis of the working principle of the AFM and nanocontact force calculation model, according to Hamaker assumptions, using continuum method established the theoretical contact force model of the AFM tip. the contact force calculation methods of contact pressure in process has been obtained. The variation of the force between the probe tip and specimen surface has been found by calculation model and programming calculation of Matlab. Provide the basis for improving the accuracy of an atomic force microscope surface inspection and error analysis

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