Development of a near-field scanning microwave microscope using a tunable resonance cavity for high resolution

We report on the operational principles and the practical implementation of a near-field scanning microwave microscope system consisting of a λ/4 coaxial resonator with a tunable resonance cavity coupled to a sharp probe tip. The changes of sensitivity and spatial resolution as a function of cavity length are clearly modulated by tuning the resonance cavity. By tuning the resonance cavity, we demonstrate improved sensitivity and spatial resolution better than 4 µm of the near-field images of a YBa2Cu3Oy thin film on a MgO substrate at an operating frequency of f = 1–1.5 GHz. We modelled the λ/4 coaxial resonator by a LCR circuit and the principles of operation can be explained by using perturbation theory, considering the radius of the probe tip, the quality factor, impedance matching, and the sample–tip distance.

[1]  D. Pozar.  Microwave Engineering , 1990 .

[2]  Michael Golosovsky,et al.  Novel millimeter‐wave near‐field resistivity microscope , 1996 .

[3]  F. Keilmann,et al.  Contrast of microwave near-field microscopy , 1997 .

[4]  Matthias Hein,et al.  Spatially resolved microwave field distribution in YBaCuO disk resonators visualized by laser scanning , 1998 .

[5]  Koji Mizuno,et al.  Experimental demonstration for scanning near-field optical microscopy using a metal micro-slit probe at millimeter wavelengths , 1997 .

[6]  Steven M. Anlage,et al.  Near‐field scanning microwave microscope with 100 μm resolution , 1996 .

[7]  X. Xiang,et al.  Tip–sample distance feedback control in a scanning evanescent microwave probe for nonlinear dielectric imaging , 2000 .

[8]  Steven R. LeClair,et al.  Evanescent microwaves: a novel super-resolution noncontact nondestructive imaging technique for biological applications , 1999, IEEE Trans. Instrum. Meas..

[9]  D. Davidov,et al.  High-spatial resolution resistivity mapping of large-area YBCO films by a near-field millimeter-wave microscope , 1996 .

[10]  P. Schultz,et al.  Nondestructive Imaging of Dielectric-Constant Profiles and Ferroelectric Domains with a Scanning-Tip Microwave Near-Field Microscope , 1997 .

[11]  F. C. Wellstood,et al.  Imaging microwave electric fields using a near-field scanning microwave microscope , 1998 .

[12]  S. R. LeClair,et al.  0.4 μm spatial resolution with 1 GHz (λ=30 cm) evanescent microwave probe , 1999 .

[13]  Fred Duewer,et al.  High spatial resolution quantitative microwave impedance microscopy by a scanning tip microwave near-field microscope , 1997 .

[14]  Jooyoung Kim,et al.  Improved surface imaging with a near-field scanning microwave microscope using a tunable resonator , 2002 .

[15]  T. Nozokido,et al.  Visualization of photoexcited free carriers by scanning near-field millimeter-wave microscopy , 2000 .

[16]  Jooyoung Kim,et al.  Millimeter-wave scanning near-field microscope using a resonant waveguide probe , 2001 .

[17]  X. Xiang,et al.  Quantitative microwave near-field microscopy of dielectric properties , 1998 .

[18]  Michael Golosovsky,et al.  COMBINED MILLIMETER-WAVE NEAR-FIELD MICROSCOPE AND CAPACITANCE DISTANCE CONTROL FOR THE QUANTITATIVE MAPPING OF SHEET RESISTANCE OF CONDUCTING LAYERS , 1998 .

[19]  F. C. Wellstood,et al.  QUANTITATIVE IMAGING OF SHEET RESISTANCE WITH A SCANNING NEAR-FIELD MICROWAVE MICROSCOPE , 1997, cond-mat/9712171.