Laboratory of Scanning Electron Microscopy
head: dr Paweł Bącal
e-mail: esem@twarda.pan.pl
phone: +48 22 697 88 60
SEM Form (link)
Laboratory Regulations (link)
By using a non-invasive electron beam, SEM creates images of both high resolution and high magnification at the same time. These analyses provide detailed information about morphology, microstructure or elemental composition of samples.
High Resolution Scanning Electron Microscope Quattro S by Thermo Fisher
The SEM allows for work in variable pressure in the chamber in 3 modes and ranges: ca. 6x10-4 Pa (High Vac), 10 Pa do 200 Pa (Low Vac), 10 Pa do 4000 Pa (Environmental Mode – ESEM). We employ water vapor as a gas, however it’s technically possible to use other gases.
This SEM allows for imaging conductive samples, sputtered with metal or carbon layer or non-sputtered and non-conductive samples. Non-sputtered, non-conductive samples can be investigated in Low Vacuum or Environmental Modes.
Samples are usually sputtered with carbon (thin layer of ca. <10 nm) using Safematic CCU-10 HV. This sputter allows for precise coting with accuracy ca. 1nm. Thick conductive layers of platinum are sputtered using Baltec plasma coater.
SEM chamber is 340 mm in diameter. Sample holder is eucentric and motorized in 5 axes what allows for movements range: 110 mm (X and Y axes), 65 mm (Z axis), tilt-15⁰ to 90⁰ and rotation 360⁰. Samples below 0,5 kg can be moved in all mentioned axes. Maximal load of sample holder is 5 kg (no tilt). Max sample length is 220 mm. Standard holder allows for examination of 18 samples/ stubs at once. (SEM stub diameter 12,7 mm).
Inside of SEM chamber can be monitored using CCD (close infrared) camera. Besides that, the SEM is equipped with 6 Mpx resolution and software for sample navigation.
The SEM electron source is filed emission gun (Schottky emiter) what allows imaging in the range of High Tension (EHT) from 0,02 kV to 30 kV. Beam current can be changed in 1 pA to 200 nA. This give resolution ca. 1 nm (SE, High Vac, High EHT) ca. 3 nm (SE, Low, Vac, Low EHT) and 2,5 nm for BSE. Magnification are in the range from 13x -1 000 000x (when displayed on the 24”monitor).
SEM Quattro S is equipped with detectors: Secondary Electrons (SE), Backscatter Electrons (BSE), Cathodoluminescence (CL), Energy-dispersive X-ray spectroscopy (EDS), Electron backscatter diffraction (EBSD).
The microscope is equipped with SE and BSE detectors suitable for all 3 vacuum modes. The BSE detectors are of concentric build which allows for both material and topographical contrast depending EHT and angle of scattering of BSE vs primary electron beam.
Energy-dispersive X-ray spectroscopy (EDS), is EDAX Octane Elect Plus. This detector has 127 eV (for Kα Mn) resolution and allows for detection elements from Be to Am. Detector window is 30mm2 and made of silicon nitrate. EDS analysis can be performed from Kα Al. (73eV) and done in the spot, line, or freeform rectangle area. During mapping each pixel is stored with full composition spectra. Results can be exported to Word or as a numeric data.
Electron backscatter diffraction (EBSD) detector EDAX Hikari Super is mid speed camera allowing to get up to 1400 fps. The SEM is equipped with OIM 8 software for EBSD data processing.
Both, EDS and EBSD are equipped with Montage function, which allows for stitching images and/or data for large area measurements into single file/image/map. Cathodoluminescence (CL) detector can work in RGB and Panchromatic modes. Wavelength range in panchromatic mode is 350-900 nm.
SE and BSE or SE and CL images can be collected simultaneously for the same Working Distance and digitally mixed/corelated. The SEM is equipped with MAP 3 software what allows scanning/imaging of large area samples and stitching into single image or correlation with images from other methods e.g. Raman spectroscopy, optical microscopy.
SEM images can be in the TIFF, BMP or JPG formats with resolution up to 25 Mpx in greyscale. Video can be done and saved in AVI format.
Microscope is equipped with accessory heating table and SE detector allowing for a short experiments up to ca. 1000⁰C regulated with 1 ⁰C accuracy. Microscope is equipped with Peltier cooling table allowing to cool down and keep the sample up to -20 ⁰C and regulated with 1 ⁰C accuracy. This allows for analysis of hydrated or partially hydrated samples in regulated humidity in the chamber. Humidity can be changed in 0-100% range. Heating or cooling samples can be performed with programed steps and ramps. When using heating or cooling stage, the sample volume is highly limited.
Philips XL20 Scanning Electron Microscope
The Philips XL20 microscope is equipped with SE detector, the catodoluminescence detector as well EDAX dual-window (UTW/Open) ECON detector for X-ray energy dispersive analysis. Fully integrated SEM/EDS system DX4-I is very convenient for user, and provides good quality standardless qualitative and quantitative analysis. Colour analog mapping is possible. This instrument provides quantitative chemical analyses, secondary electron images, and analog elemental distribution maps for use in the geological, metallurgical, ceramic, anthropological, and forensic sciences. Analyses and imaging can be done on samples as small as a few microns across. The maximal size of samples is 20mm in diameter and 10mm high. This instrument is widely used by Institute staff as well as by industrial clients.
Samples for electron microprobe imaging and analysis consist of materials that are stable in a vacuum and under a high-voltage electron beam. Specimens for quantitative analyses must be fine polished (or naturally have a flat surface). For electron microprobe analyzing non-conductive samples must be coated with thin carbon layer, that is also available in Laboratory. For SEM imaging we use a platinum coating by BALTEC SCD 005 sputter coater. Specimen mounts, electroconductive glue, tapes etc. are available in our laboratory.