The contrast formation and the achievable lateral resolution of a scanning capacitance microscope have been simulated using the finite element method. On conducting surfaces, a resolution of about 2 nm is expected with probes with about 5-10 nm radius of curvature. At smaller radii, the resolution degrades due to the decrease of the local contribution to the integral capacitance sensed by the probe. The lateral resolution is less affected by the radius of the tip than by the tip-to-conducting base distance, though sharper tips produce higher contrast. With a tip radius of approximately 25 nm, resolution of features 5 nm in diameter has been achieved on gold-coated silicon.

A simple correction of residual non-linearity of inverse capacitance displacement transducers is presented. The transducers were designed for independent probe position monitoring of a scanning probe microscope and/or linearization of the closed-loop control of a SPM scanner. The linearity of the transducers prior to compensation was tested in an SPM head using optical interferometry and the fine-tuning and efficiency of non-linearity suppression using a scaled-up model of the sensor capacitor, mounted on a micrometer.

A scanning probe microscope, combining a scanning capacitance microscope with a scanning tunneling microscope (STM) using the same probe and input electronics, has been built. The probe is shielded and its stray capacitance is less than 0.5 fF. As an input stage, a wide-bandwidth current-to-voltage converter has been applied. In the capacitance microscope mode, its phase sensitively measures the current flowing through the probe/sample capacitance. The optimum operating frequency is from 1 to 10 MHz. The achieved signal-to-noise ratio is comparable with microscopes using a videodisk pickup as the capacitance sensor. The same amplifier at reduced bandwidth serves in STM mode. Its sensitivity corresponds to standard microscopes, albeit the input bias current is larger than at good STM input stages. It can be used with tunneling currents larger than 100 pA.

The operation principle and main properties of a Scanning Capacitance Microscope (SCM) are described. It is called low-frequency, because in its design typical low-frequency techniques are utilised. The main attention is focused on its lateral resolution, signal-to-noise ratio and the possibility to detect dielectric losses.Mapping the electrostatic field of a shielded microscope probe was used to calculate the stray capacitance, flux density, sensitivity and contrast obtained on a flat conducting surface, as well as on a surface covered by a thin dielectric film. The effect of dielectric losses, represented by a parallel conductance, on the detected capacitance and the resulting phase shift has been derived.Using the results of mapping, the requirements on a SCM input stage and the possible solutions are discussed. From the point of view of frequency range and noise the best is an electrometric input stage, with input impedance represented by its capacitance.The achieved signal-to-noise ratio of the low frequency Scanning Capacitance Microscope renders the extension of the working frequency range to lower frequencies. The input stage can be optimised for a frequency range from about 1 kHz to a few MHz, with the possibility to extend it to about 10 MHz at the cost of reduced sensitivity at the lowest frequencies.

A microcomputer-controlled measuring instrument for capacitance and inductance measurement is described. It is based on an oscillator circuit with the oscillation frequency dependent on a measured element. An analysis of the oscillator used is also given. Equations for the oscillation frequency and its deviation from the resonance frequency of a frequency controlling resonance circuit are derived. The measured results can be transferred into a personal computer (PC) which can process and display these results and control the instrument via RS-232 serial interface.