Bias controlled capacitive driven cantilever oscillation for high resolution dynamic force microscopy Appl. Phys. Lett. 102, 073110 (2013) Friction measurement on free standing plates using atomic force microscopy Rev. Sci. Instrum. 84, 013702 (2013) A correlation force spectrometer for single molecule measurements under tensile load J. Appl. Phys. 113, 013503 (2013) Compact metal probes: A solution for atomic force microscopy based tip-enhanced Raman spectroscopy Rev. Sci. Instrum. 83, 123708 (2012) Note: Radiofrequency scanning probe microscopy using vertically oriented cantilevers Rev. Sci. Instrum. 83, 126103 (2012) Additional information on Appl. Phys. Lett.
High-speed constant force imaging with the atomic force microscope ͑AFM͒ has been achieved in liquid. By using a standard optical lever AFM, and a cantilever with an integrated zinc oxide ͑ZnO͒ piezoelectric actuator, an imaging bandwidth of 38 kHz has been achieved; nearly 100 times faster than conventional AFMs. For typical samples, this bandwidth corresponds to tip velocities in excess of 3 mm/s. High-speed AFM imaging in liquid will ͑1͒ permit chemical and biological AFM observations to occur at speeds previously inaccessible, and ͑2͒ significantly decrease measurement times in standard AFM liquid operation.
We have demonstrated that the atomic force microscope (AFM) operating in air may be used to pattern narrow features in resist in a noncontact lithography mode. A micromachined AFM cantilever with an integrated silicon probe tip acts as a source of electrons. The field emission current from the tip is sensitive to the tip-to-sample spacing and is used as the feedback signal to control this spacing. Feature sizes below 30 nm have been patterned in 65-nm-thick resist and transferred through reactive ion etching into the silicon substrate. We show that the same AFM probe used for noncontact patterning can be used to image the sample. In addition to eliminating the problem of tip wear, this noncontact system is easily adapted to multiple-tip arrays where each cantilever has an integrated actuator to adjust the probe height.
Cataloged from PDF version of article.A flexible system for increasing the throughput of the atomic force microscope without sacrificing imaging range is presented. The system is based on a nested feedback loop which controls a micromachined cantilever that contains both an integrated piezoelectric actuator and an integrated thermal actuator. This combination enables high speed imaging (2 mm/s) over an extended range by utilizing the piezoelectric actuator’s high bandwidth (15 kHz) and thermal actuator’s large response (300 nm/V). A constant force image, where the sample topography exceeds the range of the piezoelectric actuator alone, is presented. It has also been demonstrated that the deflection response of the thermal actuator can be linearized and controlled with an integrated diode.\ud © 1999 American Institute of Physic
We demonstrate that scanning probe electrostatic force microscopy applied to a nanoscale electronic structure can be used for studying the spatially resolved carrier quantized states as determined by the screening properties of local surface regions of the structure. The results presented for the crosssectional surface of Bi quantum wires elucidate the microscopic nature of quasi-one-dimensional confined states excited by an applied bias voltage, where the single-particle-in-a-box energy quantization competes with the wire boundary enhanced intercarrier Coulomb repulsion. [S0031-9007(99) 09105-X] The invention of the atomic force microscope [1] (AFM) has opened a new era of scanning force experiments. The second generation electrostatic force microscopy [2] (EFM) allows us to study spatially resolved ͑ϳ1 nm͒ electronic properties of surfaces containing both conducting and insulating regions, and, therefore, this technique can be applied to nanoscale quantum heterostructures. EFM measures the axial gradient of the electrostatic force acting on a small biased probe as a result of the long-range Coulomb interaction with the near-surface charges of the structure. So far, EFM has been successfully applied to detecting surface trapped charges [3], to profiling the dopant concentration in microdevices [4], and to measuring work functions [5] of various materials.Here we show how EFM can be employed to study the screening properties of a quasi-one-dimensional (1D) electron (or hole) gas excited near the cross-sectional surface of Bi quantum wires by applying a bias voltage ͑V b ͒ with respect to the nearby probe. The study reveals that EFM bias voltage spectroscopy and imaging, observed at probe-wire distances ͑h͒ nearly comparable to the Thomas-Fermi screening length (l) of the wire carriers, provide direct information on the 1D-quantized carriers states as a function of energy and spatial position. At these small distances ͑h ϳ 10 nm͒, the electrostatic attraction between the Bi wire and the capacitively coupled probe is reduced as a result of the penetration of an electric field, associated with the charged probe, into the wire subsurface region. Assuming the simplest case of a plane capacitor [6] geometry formed by the probe tip and the local surface region of the wire, the attractive electrostatic force gradient ͑F 0 ͒ acting between them is, then, to first order in ͑l͞h͒ given byIn Eqs.(1), S denotes the probe tip area, eV 0 is the electron work function of the Bi wire relative to that of the probe, and l, within the linear screening theory, is inversely related to the carrier thermodynamic density of states (TDOS) ≠n͞≠m, where m is the wire electrochemical potential controlled by the bias voltage V b . Thus, we study the TDOS of a single wire for various wire radii 30 # R , 70 nm by measuring F 0 as a function of the probe position in both the diametrical ͑x͒ and axial ͑z͒ directions, as well as by the bias voltage spectroscopy of F 0 obtained at a given point ͑x, z͒ above the wire crosssectional surface (see F...
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