The development of new two-dimensional (2D) materials may have applications in electronics. Auger electron spectroscopy (AES) is an analytical technique for surface science and materials science that can be used for surface microanalysis. It is a powerful tool for studying solid surfaces and is widely used for a variety of materials analysis and catalytic, adsorption, corrosion and wear studies. Alfa Chemistry offers AES testing to analyze 2D materials such as graphene, which is essential for understanding their properties.
For example, we determine the layer thickness by measuring the AES spectra of graphene with different number of layers. As the number of graphene layers increases, the AES spectra show distinct spectral shape, intensity, and energy characteristics. We are also able to calculate the electron inelastic mean free range of graphene layers directly from these measurements. The method allows unambiguous and high-throughput measurements of the thickness of up to six graphene layers and the detection of defects and dopants in graphene films on almost any substrate. The availability of this reliable method will allow to directly probe the growth mechanism of graphene and to explore new properties of graphene with different thicknesses on different substrates. Contact us today so we can help you with your 2D material testing!
Why STM/STS
AES is a nondestructive core-level electron spectroscopy for semi-quantitative determination of the elemental composition of surfaces, films and interfaces. AES involves irradiating a sample with an electron beam. This results in the emission of electrons at a range of energies, some of which are characteristic of the elements from which they originate. The emitted electrons are collected and the energy analyzed. AES provides information about the elements present in the outermost atomic layers of the sample surface.
Fig 1. Auger element maps of graphene layers on SiO2/Si substrate. C KLL electron map showing striking intensity contrast among the monolayer, bilayer, trilayer, and thicker graphenes. (Xu M, et al. 2010)
The great surface sensitivity and relatively low detection limits of this ultra-high vacuum method may account for its popularity. AES can discern between two elements in the periodic table that are near to one other, in addition to covering elements ranging from lithium to uranium. Furthermore, the sensitivity of AES varies by up to one order of magnitude depending on the atomic number. Chemical state information may also be derived from AES chemical shifts and lineshapes. AES may be utilized for depth profiling in combination with simultaneous ion sputtering and offers a depth resolution of 5 to 25 Å.
Our AES testing capabilities include, but are not limited to
- Material failure analysis
- Qualitative analysis of surface elements
- Semi-quantitative analysis of surface elements
- Valence analysis of surface elements
- Surface element distribution analysis
Service Detail
| Testing Services | Auger Electron Spectroscopy (AES) |
| Test Method | Auger mapping, Auger chemical state analysis, Auger depth profiling, Auger elemental identification (point and line analysis) |
| Sample Type | Film |
| Instrument Model | Agilent 4210 MP-AES |
| Lead Time | 2~3 Weeks |
Our requirements for samples are as follows:
- Sample Size: The maximum size of an AES sample is 18 mm x 12 mm and should not exceed 12 mm in height. the minimum analysis area is 0.3 µm. For disc type samples, the max diameter is 50mm.
- Sample Type: The sample must be electrically conductive, dry and non-magnetic.
- Sample Compatibility: The sample must be compatible with high vacuum environments (ca. 1 x 10-9 Torr).
- Test limitations: Not intended for magnetic samples; Not intended for biological samples; Not intended for hazardous samples; Not intended for electrically insulated samples; Not intended for radioactive samples; Not intended for explosive samples
Note: All samples are non-refundable, please contact us if you have special requirements.
Reference
- Xu M, et al. (2010). "Auger Electron Spectroscopy: A Rational Method for Determining Thickness of Graphene Films." ACS Nano. 4(5): 2937-2945.
Please kindly note that our products are for research use only.
