0.4 μm spatial resolution with 1 GHz (λ=30 cm) evanescent microwave probe

Abstract

Calibration methods of a 2 GHz evanescent microwave magnetic probe for noncontact and nondestructive metal characterization for corrosion, defects, conductivity, and thickness nonuniformities Rev. Sci. Instrum. 76, 054701 (2005); 10. 1063/1.1900683 Planar evanescent microwave imaging probes for nondestructive evaluation of materials with very high spatial resolutions and scan rates AIP Conf.In this article we describe evanescent field imaging of material nonuniformities with a record resolution of 0.4 m at 1 GHz ( g /750 000), using a resonant stripline scanning microwave probe. A chemically etched tip is used as a point-like evanescent field emitter and a probe-sample distance modulation is employed to improve the signal-to-noise ratio. Images obtained by evanescent microwave probe, by optical microscope, and by scanning tunneling microscope are presented for comparison. Probe was calibrated to perform quantitative conductivity measurements. The principal factors affecting the ultimate resolution of evanescent microwave probe are also discussed.

Nanoscale Electronic Inhomogeneity in In2Se3 Nanoribbons Revealed by Microwave Impedance Microscopy

“…And a thin surface insulating layer, equivalent to small series impedance, will not shield the capacitive coupling to sub-surface features. The AC detection is very sensitive using mostly noninvasive RF excitation (<0.1V), in contrast to electrostatic probes 15 requiring a high DC bias (>1V) to reveal the conductivity distribution.The most common design of the near-field microwave probe is an etched metal tip, which limits the resolution to several microns, backed by a massive cavity or transmission line resonator [18][19][20] . The strong contact force due to the rigid structure easily causes damage to the tip and the sample, halting the applications on practical nano-devices.…”

“…Three distinct structural phases, as seen from the high resolution TEM images and the selected-area electron diffraction (SAED) patterns in Fig. 3a, are observed in ribbons in the [11][12][13][14][15][16][17][18][19][20] growth direction. Correspondingly, typical I-V characteristics of the three phases are shown in Fig.…”

“…3b. It has been previously reported that pristine VLS-grown [11][12][13][14][15][16][17][18][19][20] In 2 Se 3 nanoribbons with superlattice structures (Fig. 3a, left) exhibit metallic behavior and room temperature R 2T as low as kilo-ohms 10 .…”

Calibration of shielded microwave probes using bulk dielectrics

“…12,13 Unlike the conventional metal-wire probe backed by a relatively massive resonator, 3,4,7,8 the cantilever probe is scalable and significantly miniaturized for better resolution. For better sensitivity, metal traces rather than lossy doped Si lines 14,15 were patterned on nitride cantilevers.…”

“…[3][4][5][6][7][8] The non-local stray field contribution not only compromises the spatial resolution but also complicates the quantitative analysis of tip-sample interaction. Calibration of the microscope output using bulk samples [9][10][11] is therefore difficult, if not totally impossible.…”