Cathodoluminescence for Materials Science

Cathodoluminescence for materials science

Ceramics, dielectrics, and (compound) semiconductors play an important role in many devices and functional materials, including scintillators, phosphors, high-power electronics light-emitting-diodes, diode lasers, and solar cells amongst others. Nanostructuring is employed increasingly for optimization of the optical properties in such materials. Cathodoluminescence can be used to study these materials (both in bulk and in nanostructured materials) and to determine their light-emitting properties at the nanoscale.

By combining the spectral sensitivity with the high spatial resolution of the cathodoluminescence imaging technique, subtle changes in the output spectrum, defect luminescence, angular profile, and emission polarization can be analyzed on a deep-subwavelength scale. This can be used for fundamental studies of the physical and chemical processes that govern their properties as well as metrology, quality control, and failure analysis for industrial applications.

Cathodoluminescence spectra of a selection of materials

Figure 1: Cathodoluminescence spectra of a selection of materials demonstrating the relevance of the technique for a large variety of applications.

 

Gallium nitride imaged with cathodoluminescence

Figure 2: Gallium nitride microwire with a radial indium gallium nitride quantum well developed for lighting applications. Growth defects as well as variations in the quantum well properties lead to variations in the light output which can be imaged with cathodoluminescence. Such measurements can be used to determine the nanoscale properties of these materials and overall device performance.

 

Monte Carlo Beam Tracing Simulations for Incoherent Cathodoluminescence Emission

Incoherent cathodoluminescence emission occurs when the material is excited with an electron beam, and then the primary electrons decelerate and deposit their energy into the material. The size of this interaction volume depends on two factors:

  • Primary electron energy (controlled by the acceleration voltage in the microscope)
  • Density and atomic composition of the material

Si diplot color

In order to select the appropriate electron energy for a given experiment, it is valuable to know the interaction volume (penetration depth and width). By understanding it is possible to estimate what parts of your material are excited in an experiment. To help you with your cathodoluminescence research we have created a database of interaction volumes for a set of commonly studied materials in CL, such as Sapphire, Diamond, Zircon, Silicon, Gallium Nitride, Gallium Arsenide and more. 

The full 3D interaction data is organised as a list of [X, Y, Z, E] values for each electron. To get access to the database, which also includes  the Casino simulation setup file (“material”.sim) and raw data output (“material”_”voltage”kV.dat) (as “material”_raw_data.zip), please click here:

Get access to database

 


 

 

Cathodoluminescence detection system

The SPARC is a cathodoluminescence detector that is designed and produced by Delmic. This system is an ideal solution for researchers in materials science since it can be retrofitted to any scanning electron system (SEM) to produce high-performance cathodoluminescence images.

 See this page or visit our blog to learn more about the SPARC system.

 

SPARC cathodoluminescene detection system

Other CL applications