X-ray photoelectron spectroscopy (XPS) depth profiling

XPS is a semi-quantitative technique used to measure the elemental composition of material surfaces. In addition, it can also determine the binding state of the atoms. XPS is a surface-sensitive technique. Typical probing depth is 3-9 nm, and detection limits range roughly between 0.1 and 1 atomic %. XPS can measure elements from Li to U. The elemental composition is reported in at.% and measured on 1 area of a few 100 µm. Upon request, we can measure smaller areas or depth profiles, and a binding state determination can also be provided. Measurements are typically performed using one of the following instruments: PHI Genesis, Thermo Fisher ESCALAB 250Xi, PHI Quantum 2000. Synchrotron XPS is also available. Contact us for more information and a quote for your project.

Auger Electron Spectroscopy (AES) is a surface-sensitive technique (3-9 nm) used for compositional analysis and depth profiling, providing data on the elemental composition in depth. Secondary electron images can also be provided. AES is a very useful technique to measure patterns since it has a beam size that can go down to a few nm.

Imaging of the sample using scanning electron microscopy (SEM). Typically, several images are taken with varying magnifications to get a good overview of the sample. Non-conductive samples can be prepared with a metallic coating to allow imaging. For cross-section measurement, additional preparation might be needed: FIB, BIB or freeze fracturing. If compositional analysis is also needed, please see the SEM-EDX measurement.

Rutherford Backscattering Spectrometry (RBS) can be used to measure the composition of solid samples quantitatively at the surface as well as depth profiling. RBS is used for the analysis of heavy elements and can be combined with ToF-ERDA when lighter elements also need to be analyzed. Elements with similar mass can be difficult to differentiate.

This metal screening analysis includes the semi-quantitative determination of 70 elements. The method can be used, for example, to determine the background concentrations of metals in environmental samples or to study the elemental distribution of unknown samples. Screening is also often performed to assess which metals should be analyzed by a quantitative method. The measurement is performed using a high-resolution ICP-MS technique (ICP-SFMS), which can identify very low elemental concentrations. A semi-quantitative determination of the following elements is included: Ag, Al, As, Au, B, Ba, Be, Bi, Br, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, I, Ir, K, La, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Os, P, Pb, Pd, Pr, Pt, Rb, Re, Rh, Ru, S, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn and Zr. However, please note that some elements may not be determinable due to matrix interference. During this semi-quantitative analysis, the instrument is calibrated for about 30 elements and the rest of the analytes are quantified using sensitivity factors for calibrated elements with similar mass and first ionization potential considering isotope abundances. Quantitative analysis is also available at an additional price. During this analysis, all elements are calibrated (excluding halogens and Os). Please ask for an offer for this service.

Determination of carbon, hydrogen, nitrogen, sulfur, and oxygen content of an organic sample. CHNS analysis (”LECO analysis”) is performed using a flash combustion method, where the sample is combusted under 25 kPa of O2 at an elevated temperature (1000 °C), followed by gas chromatography separation and detection using a thermal conductivity detector. Oxygen is analyzed by reduction on granulated carbon at 1480 °C, utilizing high-temperature thermal decomposition and conversion of oxygen into carbon monoxide before gas chromatography separation and detection with a thermal conductivity detector. The sample can be either solid or liquid, but water in the sample affects the results. In the case of aqueous samples, it is possible to dry the sample before analysis. The price includes two parallel measurements. The results are reported as wt-% of the initial sample. The ash, drying and dry loss measurements will increase the minimum required sample material need to 300 mg. The analysis gives the total carbon, hydrogen, nitrogen, sulfur, and oxygen content of the material, but it does not identify any chemical structures. The measurement can be combined with other methods, such as GC-MS, 1H, and 13C NMR, to perform substance structure identification. Possible element packages: O, CHNS, and CHNOS.

GC-MS analysis of 16 PAH compounds, which are listed as high-priority pollutants by the U.S. Environmental Protection Agency (EPA). The analyzed PAH compounds are: naphthalene [CAS: 91-20-3], acenaphthylene [CAS: 208-96-8], acenaphthene [CAS: 83-32-9], fluorene [CAS: 86-73-7], phenanthrene [CAS: 85-01-8], anthracene [CAS: 120-12-7], fluoranthene [CAS: 206-44-0], pyrene [CAS: 129-00-0], benz(a)anthracene [CAS: 56-55-3], chrysene [CAS: 218-01-9], benzo(b)fluoranthene [CAS: 205-99-2], benzo(k)fluoranthene [CAS: 207-08-9], benzo (a) pyrene [CAS: 50-32-8], dibenzo(ah)anthracene [CAS: 53-70-3], benzo (ghi) perylene [CAS: 191-24-2], indeno (123cd) pyrene [CAS: 193-39-5].

Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA) measurement for determining the elemental concentrations of thin films. ToF-ERDA is capable of identifying all elements, including various hydrogen isotopes. It provides elemental depth profiles by determining the concentration of each element at different depths within a sample. Typically, the method achieves detection limits ranging from 0.1 to 0.5 atomic percent and depth resolution between 5 and 20 nm. It is suitable for analyzing films with thicknesses between 20 and 500 nm. For accurate measurements, the sample surface should be smooth, with a roughness of less than 10 nm. The method is inherently quantitative when analyzing thin films on typical substrates, such as silicon (Si), gallium nitride (GaN), silicon carbide (SiC), gallium arsenide (GaAs), or indium phosphide (InP). So, reference samples are not needed to obtain quantitative results. The technique is particularly useful when analyzing light elements due to its good detection limits. In addition to typical ToF-ERDA measurements, we also offer LI-ERDA (also referred to as Foil ERDA) for more precise determination of hydrogen isotopes. The detection limits with LI-ERDA are typically around 0.01 atomic percent, and depth resolutions of ~1nm can be achieved. LI-ERDA only allows detection of hydrogen isotopes.

Lignin sample ash content measurement at 525°C. The result is expressed as a mass percentage of the ash from the initial sample on a dry matter basis.

X-Ray Reflectometry (XRR) analysis is used to measure the density (g/cm3), thickness (nm), and roughness (nm) of thin films. The method is applicable to the characterization of single- or multilayered thin films, as it provides information on the thickness and density of individual layers of the sample material as well as the roughness of the interphases. Greatest accuracy for XRR thickness measurements is generally achieved for samples containing 1-150 nm thick surface layers with under 5 nm RMS roughness. Thicker films and coatings with rougher surfaces can also be characterized, but the accuracy of thickness determination decreases as the thickness and roughness of the film or film stack increase. >150 mm wafers are typically cut to fit the sample holder. Please let us know if you need testing for larger wafers that cannot be cut into pieces. The available temperature range for XRR measurements is 25-1100 °C, and crystallinity can be studied as a function of temperature. The measurements can be performed under a normal atmosphere, inert gas, or vacuum. Measurements are typically performed using one of the following instruments: Rigaku SmartLab, Panalytical X'Pert Pro MRD, Bruker D8 Discover. Please let us know if you have a preference for a specific instrument.