Point spread function (PSF) deconvolution is an attractive software-based technique for resolution improvement in the scanning electron microscope (SEM) because it can restore information which has been blurred by challenging operating conditions. In Part 1, we studied a modern PSF determination method for SEM and explored how various parameters affected the method's ability to accurately estimate the PSF. In Part 2, we extend this exploration to PSF deconvolution for image restoration. The parameters include reference particle size, PSF smoothing (K), background correction, and restoration denoising (λ). Image quality was assessed by visual inspection and Fourier analysis. Overall, PSF deconvolution improved image quality. Low λ enhanced image sharpness at the cost of noise, while high λ created smoother restorations with less detail. λ should be chosen to balance feature preservation and denoising based on the application. Reference particle size within ±0.9 nm and K within a reasonable range had little effect on restoration quality. Restorations using background-corrected PSFs had superior quality compared with using no background correction, but if the correction was too high, the PSF was cut off causing blurrier restorations. Future efforts to automatically determine parameters would remove user guesswork, improve this method's consistency, and maximize interpretability of outputs.

Electron beam-induced carbon contamination is a balance between simultaneous deposition and erosion processes. Net erosion rates for a 25 nA 3 kV beam can reduce a 5 nm C coating by 20% in 60 s. Measurements were made on C-coated Bi substrates, with coating thicknesses of 5–20 nm, over a range of analysis conditions. Erosion showed a step-like increase with increasing electron flux density. Both the erosion rate and its rate of change increase with decreasing accelerating voltage. As the flux density decreases the rate of change increases more rapidly with decreasing voltage. Time-dependent intensity (TDI) measurements can be used to correct for errors, in both coating and substrate quantifications, resulting from carbon erosion. Uncorrected analyses showed increasing errors in coating thickness with decreasing accelerating voltage. Although the erosion rate was found to be independent of coating thickness this produces an increasing absolute error with decreasing starting thickness, ranging from 1.5% for a 20 nm C coating on Bi at 15 kV to 14% for a 5 nm coating at 3 kV. Errors in Bi Mα measurement are <1% at 5 kV or above but increase rapidly below this, both with decreasing voltage and increasing coating thickness to 20% for a 20 nm coated sample at 3 kV.

Quantification of first series transition metal Lα X-rays is hampered by absorption and in some cases transition probabilities (fluorescence yields) varying with chemical bonding. Compound mass absorption coefficients for Fe Lα were measured in the olivine solid solution series [Forsterite (Mg2SiO4) to Fayalite (Fe2SiO4)] and the mass absorption coefficients for Fe Lα absorbed by Fe were calculated. The mass absorption coefficients vary systematically between Fo83 and Fo0. Using the measured mass absorption coefficients for both standard and unknown and by correcting for a systematic discrepancy, consistent with varying partial fluorescence yields, a good agreement between calculated k-ratios and measured k-ratios is achieved. The systematic variations allow quantification of unknown k-ratios. The described method of quantification requires modification of matrix correction routines to allow standards and unknowns to have different mass absorption coefficients, and to incorporate solid solution mass absorption coefficients and partial fluorescence yield corrections derived from regression of experimental data.

The effect of carbon contamination on the analysis of carbon-coated silicate minerals at 5 kV for X-ray energies 0.7–4 keV is examined. For individual spot analyses, carbon is found to deposit adjacent to the beam spot forming ring-shaped deposits with no impact on the analysis. Carbon contamination becomes important for closely spaced analyses such as multipoint transects, where each subsequent analysis overlaps the carbon ring of the previous analysis. X-ray intensity loss due to contamination is most severe for low-overvoltage elements such as Ca K consistent with carbon deposition effectively reducing beam energy. Rates of contamination are calculated and the use of a liquid nitrogen cold trap is shown to greatly reduce the amount of carbon deposited. A complimentary empirical correction is developed to correct for X-ray intensity loss from measured carbon, assuming the carbon is a film, and is compared with corrections derived from thin film calculations. PENELOPE electron probe microanalysis (PENEPMA) calculations confirm that asymmetry of the carbon deposition can be ignored for X-ray energies where intensity loss is predominantly through energy loss of beam electrons. Using a cold trap and/or an empirical correction high spatial resolution analysis (ca. 400 nm between points) is achievable with analytical errors of ca. 1–3%.

This paper introduces a VDD generator for the ultrahigh frequency (UHF) passive Radio-frequency identification (RFID) tag, consisting of an RF-limiter, an NMOS rectifier, a DC-limiter, and a regulator. The proposed NMOS rectifier utilizes diode-connected native NMOS transistors with ultralow-threshold voltage instead of Schottky diodes. The theoretical equations for predicting the performance of the VDD generator are provided and verified by both simulation results in 90 nm CMOS process. The proposed VDD generator generates a 1.19-V stable output voltage with low-power dissipation and a 26.96% larger power conversion efficiency under conditions of 50 Ω antenna, 900 MHz, −23 dBm input power and 1 M DC output load. The chip area of the proposed VDD generator is only 105 × 85 μm. The simulation results indicated that the presented novel VDD generator is capable to provide efficient, stable, and input-independent power supply for Passive UHF RFID tag

Conventional electron-probe microanalysis has an X-ray analytical spatial resolution on the order of 1–4 μm width/depth. Many of the naturally occurring Fe–Si compounds analyzed in this study are smaller than 1 μm in size, requiring the use of lower accelerating potentials and nonstandard X-ray lines for analysis. Problems with the use of low-energy X-ray lines (soft X-rays) of iron for quantitative analyses are discussed and a review is given of the alternative X-ray lines that may be used for iron at or below 5 keV (i.e., accelerating voltage that allows analysis of areas of interest <1 μm). Problems include increased sensitivity to surface effects for soft X-rays, peak shifts (induced by chemical bonding, differential self-absorption, and/or buildup of carbon contamination), uncertainties in the mass attenuation coefficient for X-ray lines near absorption edges, and issues with spectral resolution and count rates from the available Bragg diffractors. In addition to the results from the traditionally used Fe Lα line, alternative approaches, utilizing Fe Lβ, and Fe Ll-η lines, are discussed.

Previously, imaging and analysis with cathodoluminescence (CL) detectors required using high accelerating voltages. Utilization of lower accelerating voltage for microanalysis has the advantages of reduced beam-specimen interaction volume, and thus better spatial resolution, as well as reduction in electron beam induced damage. This article will highlight recent developments in field emission gun–scanning electron microscope technology that have allowed acquisition of high spatial resolution CL images at very low accelerating voltages. The advantages of low kV CL imaging will be shown using examples of a geological specimen (shale) and a specimen of an industrial grade diamond.

Specimen quality is vital to (scanning) transmission electron microscopy (TEM) investigations. In particular, thin specimens are required to obtain excellent high-resolution TEM images. Conventional focused ion beam (FIB) preparation methods cannot be employed to reliably create high quality specimens much thinner than 20 nm. We have developed a method for in situ target preparation of ultrathin TEM lamellae by FIB milling. With this method we are able to routinely obtain large area lamellae with coplanar faces, thinner than 10 nm. The resulting specimens are suitable for low kV TEM as well as scanning TEM. We have demonstrated atomic resolution by Cs-corrected high-resolution TEM at 20 kV on a FIB milled Si specimen only 4 nm thick; its amorphous layer measuring less than 1 nm in total.

A brief description is given of the events surrounding the development of biological X-ray microanalysis during the last 30 years, with particular emphasis on the contribution made by research workers in Cambridge, UK. There then follows a broad review of some applications of biological X-ray microanalysis. A more detailed consideration is given to the main thrust of current procedures and applications that are, for convenience, considered as four different kinds of samples. Thin frozen dried sections which are analyzed at ambient temperatures in a transmission electron microscope (TEM); semithin frozen dried sections which are analyzed at low temperature in a scanning transmission electron microscope (STEM); thick frozen hydrated sections which are analyzed at low temperature in a scanning electron microscope (SEM), and bulk samples which are analyzed at low temperature in the same type of instrument. A brief outline is given of the advantages and disadvantages of performing low-voltage, low-temperature X-ray microanalysis on frozen hydrated bulk biological material. The article concludes with a consideration of alternative approaches to in situ analysis using either high-energy beams or visible and near-visible photons.