A Word on Cathodoluminescence

Johnson, Cathy

February 03, 2013

A Word on Cathodoluminescence

Cathodoluminescence microanalysis is an emerging technique that is fast gaining popularity in the world of materials science. CL is a light emission phenomena resulting from the electron beam excitation of a luminescent material. As electronic transitions occur between the conduction and valence bands, CL photons are generated and detected. Electronic transitions due to defect levels within the band gap, particularly in the case of semiconductors and devices, can also influence CL data. Data acquisition results in a mapping of the optical activity for a specimen.

CL data can indicate defects such as imperfections or impurities within the microstructure of a material phase. These defects can have an effect on the material’s optical, electrical and mechanical properties. Utilizing the high resolution capability of a SEM or STEM, a spectrum can be acquired at each point location (i.e. hyperspectral imaging). As such, it serves as an important spectroscopy and imaging technique in the characterization of materials. Image resolution is dependent on instrument configuration, experimental parameters and specimen interaction, but can range from <10 nanometers to the micron level.

Panchromatic cathodoluminescence image of cassiterite (SnO₂) mineral.
Credit: Scott Wight (National Institute of Standards and Technology – NIST), Ed Vicenzi (Smithsonian Institution), Doug Meier (National Institute of Standards and Technology – NIST), Kurt Benkstein (National Institute of Standards and Technology – NIST)
Source: Smithsonian National Mineral Collection
Preparation: Cut and polished with the Leica EM TXP
Data collection: FEI Company Quanta^TM 200F SEM with Gatan, MonoCL4 Elite System

The first MAS Cathodoluminescence Topical Conference was hosted October 24–28, 2011 by the National Institute of Standards and Technology (NIST) in Gaithersburg, MD. This conference was sponsored by the Microbeam Analysis Society (MAS), and was co-sponsored by the Australian Microbeam Analysis Society (AMAS). The four day program included a pre-conference tutorial targeted for the CL novice on October 24^th. The remaining three days included a combination of technical presentations, hands-on laboratory demonstrations and a contributed poster session. Presentation topics included: CL theory, data quantification, advances in instrumentation, analysis and databases. Applications in geological, semiconductor and nanomaterial disciplines including sample preparation and Correlative CL in conjunction with complementary techniques such as EBIC and EBSD were also addressed.