How Cathodoluminescence Microscopy Helps in Semiconductor Analysis

June 13, 2023 Dave Cockett Uncategorized

Cathodoluminescence microscopy is a powerful technique used for semiconductor analysis at the nanoscale. It involves the stimulation of a sample with a high-energy electron beam in an electron microscope, which results in the emission of light or photons known as cathodoluminescence (CL). This technique surpasses the limitations of optical microscopes by providing sub-nanometer spatial resolution, allowing for the study of various properties at the nanoscale.

The purpose of this blog post is to explore the role of cathodoluminescence microscopy in semiconductor analysis. By delving into the principles, applications, and advantages of this technique, we aim to provide scientific experts with valuable insights into its use and significance in the field of semiconductor analysis.

What is Cathodoluminescence?

Cathodoluminescence refers to the emission of light or photons from a material when stimulated by a cathode ray or high-energy electron beam. This phenomenon occurs due to the interaction between the electron beam and the material, resulting in various processes that can be harnessed for different microscopy techniques.

Many materials exhibit cathodoluminescence when excited by radiation, including phosphors, dielectric materials like glasses and ceramics, as well as direct bandgap semiconducting materials such as GaAs and InP.1 These materials emit light through quantum mechanical transitions induced by the electron beam excitation.

Cathodoluminescence in Semiconductor Analysis

Cathodoluminescence microscopy is employed in scanning electron microscopes (SEMs) or scanning transmission electron microscopes (STEMs) to characterise semiconductor materials. It enables the analysis of composition, optical properties, and electronic properties, providing valuable insights into the morphology, microstructure, and chemistry of the materials at the micro- and nano-scale.

Broadband excitation source

The electron beam used in cathodoluminescence microscopy is a broadband excitation source, allowing for the inspection of the complete spectral range of the sample, from deep UV to infrared.2

Correlation with structural information

Cathodoluminescence microscopy can be combined with other electron microscopy techniques, such as scanning electron microscopy (SEM) or transmission electron microscopy (TEM), to obtain information about the composition, optical and electronic properties of a sample. This data can be correlated with composition, microstructure and morphology at the subnanoscale3. As a result, a comprehensive understanding of the relationship between structure and function in semiconductor materials can be achieved.

High spatial resolution

Cathodoluminescence microscopy can operate at a spatial resolution of about 20 nm, and some systems enable sub-nm resolution. This allows for detailed investigation of the electronic and optical properties of semiconductor structures at the nanoscale.

Probeless and contactless

One of the key benefits of cathodoluminescence is that it’s probeless and contactless. This significantly reduces the risk of contamination or damage to the sample, as it remains untouched while being analysed.

Versatility

Cathodoluminescence microscopy can be used to probe various material properties, such as local band edge emission, local defect band emission, point defects, delocalized defects, damage and strain to the material, dopant distribution, and carrier diffusion. These characteristics are crucial for industrial applications and fundamental research. Cathodoluminescence microscopy can also be used to analyse a range of non-metallic materials, including insulators, semiconductors, ceramics and more.

Overall, cathodoluminescence microscopy offers several unique advantages for semiconductor analysis, providing valuable insights into the electronic and optical properties of materials at the nanoscale. For semiconductors and their components to be effective in industrial applications, it is crucial that experts can analyse the above mentioned properties with cathodoluminescence microscopy for failure analysis, quality assurance and future developments.

Cathodoluminescence with Blue Scientific

Blue Scientific provides a range of systems that can facilitate cathodoluminescence with electron microscopes. We currently have the ChromaCL2 iBSED Detector and Monarc CL Detector, suitable for a range of sample analysis applications.