Defect Counting and Visualization in Optoelectronic Materials Using Cathodoluminescene

The emergence of new materials has opened the doors to nano-electronic and optoelectronic devices with new or improved capabilities. For example, III-V based alloys have transformed the LED industry seeking applications in high power electronics, and may accelerate micro-electronic devices in the near future. Unfortunately, the presence of highly concentrated crystallographic or impurity defects limit the wide scaled implementation of III-V based alloys. Since such defects are typically of sub-nanometric size, they cannot be easily observed directly. Defect metrology is by consequence of great significance to evaluate fabrication processes.

Traditional Methods and Drawbacks

Traditionally, three methods are used to establish the density of defects in optoelectronic devices.

TEM image of a GaN sample exhibiting defects.

CL image of the same sample. Defects appear as dark spots. The yellow dots point the defects that are detected by the Attolight proprietary software.

Advantages of Cathodoluminescence Microscope

On the other hand, cathodoluminescence (CL) microscope addresses these limitations by combining large field of view and small probe size. The Attolight CL microscope has unique features that make defect imaging and counting in optoelectronic devices more precise and cost effective.

Defect density counting: Comparison of the Attolight CL microscope with TEM and AFM techniques

TEM AFM Attolight CL
Sample 1 2.06 x 109 cm-2 2.07 x 109 cm-2
Sample 2 2.90 x 108 cm-2 2.51 x 108 cm-2

This information has been sourced, reviewed and adapted from materials provided by Attolight.

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