Contrast analysis of near-field scanning microscopy using a metal slit probe at millimeter wavelengths

Abstract

We describe an analytical method for investigating the signal contrast obtained in near-field scanning microscopy using a metal slit probe. The probe has a slit-like aperture at the open end of a rectangular or a parallel plate waveguide. In our method, the electromagnetic field around the metal slit aperture at the probe tip is calculated from Maxwell's equations in the Fourier domain in order to derive the electrical admittance of a sample system consisting of layered dielectrics as seen from the probe tip. A simple two-port electrical circuit terminated by this admittance is then established to calculate the complex reflection coefficient of the probe as a signal. The validity of the method is verified at millimeter wavelengths by a full-wave high frequency 3-D finite element modeler and also by experiment. The signal contrast when varying the short dimension of the slit aperture, the separation between the probe tip and the sample, and the sample thickness are successfully explained in terms of the variation in the product of the admittance and the characteristic impedance of the waveguide at the probe tip. In particular, the cause of the local minimum in the signal intensity when varying the separation is clarified.

Резонансная Микроволновая Спектроскопия Полупроводников С Микронным Разрешением

“…Проблема заключается в сложной (зачастую не известной с достаточной точ-ностью) геометрии зондов микроскопов. Для построения аналитических моделей [22][23][24][25][26][27][28] используются упрощающие предположения, снижающие точность описания. Дополнительным осложняющим обстоятельством служит тот факт, что параметры моделей зависят от характеристик исследуемого объекта, т.е.…”

Microwave Resonant Spectroscopy of Semiconductors with Micrometer Resolution

“…The problem refers to a complicated geometry (often is not known clearly enough) of the microscope probes. Simplification assumptions are used for developing analytical models [22][23][24][25][26][27][28] that decrease the accuracy of description. An additional complicating factor is that the parameters of the models depend on the characteristics of the studied object, i.e.…”