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Electron-beam-induced deposition of various materials from suitable precursors has represented an established branch of nanotechnology for more than a decade. A specific alternative is carbon deposition on the basis of hydrocarbons as precursors that has been applied to grow various nanostructures including masks for subsequent technological steps. Our area of study was unintentional electron-beam-induced carbon deposition from spontaneously adsorbed hydrocarbon molecules. This process traditionally constitutes a challenge for scanning electron microscopy practice preventing one from performing any true surface studies outside an ultrahigh vacuum and without in-situ cleaning of samples, and also jeopardising other electron-optical devices such as electron beam lithographs. Here we show that when reducing the energy of irradiating electrons sufficiently, the e-beam-induced deposition can be converted to e-beam-induced release causing desorption of hydrocarbons and ultimate cleaning of surfaces in both an ultrahigh and a standard high vacuum. Using series of experiments with graphene samples, we demonstrate fundamental features of e-beam-induced desorption and present results of checks for possible radiation damage using Raman spectroscopy that led to optimisation of the electron energy for damage-free cleaning. The method of preventing carbon contamination described here paves the way for greatly enhanced surface sensitivity of imaging and substantially reduced demands on vacuum systems for nanotechnological applications.

Progress in materials science is inseparably connected with development of new analytical methods which make possible to observe the materials microstructure with high sensitivity. The aim of the present study is shown that scanning low energy electron microscopy (SLEEM) has a significant impact in advance of a fundamental understanding of the evolution of microstructure upon semi-solid processing. This paper deals with the application of the ultra high vacuum scanning low energy electron microscopy (UHV SLEEM) to the study of microstructure of X210Cr12 steel after the formation in semi-solid state and the study of the annealing of deformed metastable austenite. Examples from these specimens show that the contrast between differently oriented grains in polycrystalline materials is very sensitive to the parameters such as energy of the primary beam, working distance and detection of high angle backscattered electrons.

An overview of recent developments in very low energy scanning electron microscopy is presented. Electron optical aspects are briefly summarized including the low energy beam formation in a cathode lens equipped column, comparison of the sequential and overlapped electric and magnetic fields in the objective lens, and detection issues including extension to the transmitted electron mode as well as to the multichannel detection of signal sorted according to the polar angle of emission. In addition to the acquisition of contrasts specific for the very low energy range, advantages of detection of electrons backscattered to large angles from the surface normal are demonstrated on selected application examples.

By introducing a cathode lens below or inside the objective lens of a scanning electron microscope, many experiments similar to those typical of the LEEM method can be performed. The conditions for the diffraction of slow electrons are modified by the convergence of the primary beam, and challenges include the necessity of managing the signal species propagating along the optical axis in a direction opposite to that of the primary beam. However, even a simple implementation, providing the integral dark-field signal only, has not only delivered plenty of results in the very low energy range below 50 eV, but the performance in the range of hundreds of eV and units of keV has also been substantially improved. The scanning LEEM method is illustrated using experimental results acquired by additionally employing multichannel detection and detection of transmitted electrons.

The real point resolution of an SEM image is treated in a two-dimensional model where the decisive quantity is the root-mean-square distance of the emitted electron from the pixel centre. This quantity is computed taking into account the direct illumination of the specimen surface by the primary spot the dimensions of which are given by the electron optical column and the indirect illumination from a virtual source of the backscattered electrons in the specimen depth the properties of which depend on the specimen. Because the second order movement of the full distribution is considered here instead of some measure of the central narrow peak of secondaries, the backscattered electron influence significantly deteriorates the resulting resolution. Reasonable approximations regarding both contributions, particularly the Monte-Carlo modelling of the backscattering process by algorithms providing acceptable results down to 1 keV and the approximate relations describing the secondary and backscattered electron emission again down to 1 keV, enabled us to bring the considerations up to numerical results for some typical instruments, namely a "cheap" SEM, a "top" SEM and a low-energy SEM (LESEM) adapted from the cheap SEM by using the cathode lens. The optimum landing energy providing the best point resolution, computed for the individual chemical elements, falls into the range 1 to 5 keV for the cheap SEM and it remains around 1 keV (with some uncertainty caused by the approximations mentioned) for both the top SEM and LESEM. Similarly, the real resolution for the elements ranges between 16 and 45 nm when the cheap SEM with a 3.4 nm nominal spotsize at 30 keV is used, between 3.5 and 9 nm for the 0.7 nm top SEM and between 5.5 and 7 nm for the cheap SEM adapted to LESEM.

Some problems of scanning Auger electron microscopy (SAEM) concerning instrumentation and experimental techniques are described and briefly discussed in the light of the fundamental limitations of the method set by the nature of the phenomena themselves.

The paper describes the physical basis and the structure of the algorithms included in the software package for automatic spectrum processing developed recently as an option to the Tesla BP 350.1 Automatic Auger electron spectrometer.

This paper describes the principles of the method of electron spectra collection based on the spectrum statistics, and its realization by a microcomputer system developed for electron spectrometer control and for data processing. Electrons passing through the bandpass energy filter are detected as pulses and counted by a 24-bit counter. Another counter collects the pulses of a reference signal; for fixed timing, the reference counter is clocked with an oscillator. Using the total secondary emission current as the reference signal, the emission fluctuations are eliminated and, finally, the signal from a second broader concentric window allows us even to eliminate the background. The measurement of the single spectrum run in any energy interval is governed by the ratio of signal to statistical noise. This value defines the binary order of the reference counter carry signal that stops the signal sample collection. In this way a constant value of signal-to-noise ratio is kept throughout the whole spectrum. The 24-bit sample is then fitted to a 16-bit window according to a preselected value of “sensitivity”. The 16-bit result is stored or accumulated in the “immediate” memory. A reduced 8-bit sample is stored and possibly displayed on a screen. To improve the signal-to-noise ratio, easily-observable fast spectrum runs are accumulated. In this case the microcomputer calculates the new measurement timing so that after the accumulation of 256 runs all bits in the selected dynamical range of measurement are statistically valid. Some results are presented to illustrate the advantages of the microcomputer controlled spectrum accumulation method with measurement time correction. They are compared with single sweep measurements obtainable with classical instruments.