The nanoscilloscope: Combined topography and AC field probing with a micromachined tip

Abstract

Articles you may be interested inDevelopment of a multifunctional surface analysis system based on a nanometer scale scanning electron beam: Combination of ultrahigh vacuum-scanning electron microscopy, scanning reflection electron microscopy, Auger electron spectroscopy, and x-ray photoelectron spectroscopy Rev.Fabrication of gold nanostructures on a vicinal Si(111) 7×7 surface using ultrahigh vacuum scanning tunneling microscope and a gold-coated tungsten tip Silicon metal-oxide-semiconductor field-effect transistor with gate structures defined by scanned probe lithography J.We introduce a new concept for combined probing of topography and local AC fields, and report preliminary results of tip fabrication and scale-model measurements. The scanning force microscope ͑SFM͒ has been recently used to measure AC fields using the nonlinear response of the cantilever to voltage differences between the sample and scanning tip. By contrast, we extend the concept of near-field scanning optical microscopy ͑NSOM͒ down in frequency by employing a non-cutoff coaxial micromachined waveguide/tip, maintaining the topographic and tip-sample distance control capabilities of the SFM. Because this instrument will be used to measure both AC fields and topography with nanometer-level localization and better than nanosecond temporal resolution, we call it a nanoscilloscope.

Localized picosecond resolution with a near-field microwave/scanning-force microscope

“…18 This not only enables a calibration of the voltage scale but points out the bandwidth limitation of the 95 pF/m output coaxial cable. We estimate values for R cantilever Ϸ10 ⍀, C cantilever Ϸ0.03 pF, and L bondwire Ϸ0.5 nH, and the tip-sample capacitance C tip at ϳ0.4 pF, a value corresponding to the area of the shield opening at a ϳ2 nm tip-sample working distance.…”

“…While this is already the smallest reported coaxial structure to be used for field measurements, we are developing a micromachined version with a ϳ100 nm diameter for even greater field confinement, ease of assembly to a cable, and the attendant advantages of batch fabrication. 18 The sample, a NLTL on GaAs, is a high-impedance coplanar waveguide transmission line periodically loaded with reverse-biased Schottky diodes ͑inset, Fig. 3͒ to compress an input sinusoid into a sawtooth waveform having a pico-or sub-picosecond edge, here a falling edge due to the polarity of the diodes.…”

High-frequency near-field microscopy

“…Coaxial waveguides have a twofold advantage in that there is no cutoff wavelength limit and that the outer conductor shields the signal, reducing noise levels significantly. Thus, flanged or flange-less open-ended coaxial waveguides have been studied in theory [151][152][153][154][155][156][157][158][159][160] and used for semiconductor, superconductor and dielectric characterization, 153,154,161,162 IC probing 163 and even quality assurance of processed food. 164 The resolution of these systems without tip-sample distance control is in the millimeter to centimeter range.…”

Tapping mode microwave impedance microscopy

“…3,4 Such a strong contact force easily damages both the tip apex and the sample surface, preventing its applications on soft matter, nanoscale materials, and nanodevices. The advent of cantilever probes on atomic force microscope ͑AFM͒ platforms [5][6][7][8][9] significantly alleviates the contact force down to 10 −9 -10 −7 N, while detrimental effects inherent in contact mode AFM still exist. More importantly, a number of problems are associated with contact mode microwave imaging.…”