Fast and simple – novel crystallographic orientation mapping by Raman microscopy.

Session

PSA.3 - Semiconductors & Devices

Authors

Dr. Christian Holzner (2), Dr. Oleksii Ilchenko (1, 3), Dr. Yurii Pilhun (1), Dr. Florian Bachmann (2), Dr. Erik Lauridsen (2)

Affiliations

1. Lightnovo ApS
2. Xnovo Technology ApS
3. Technical University of Denmark

Keywords

Crystallography, Imaging, Microscopy, Orientation-mapping, Raman, Semiconductor

Abstract text

We introduce a novel method of quantitative Raman Imaging for Crystallographic Orientation (qRICO) analysis that is capable of performing fast and simple-to-use orientation mapping of materials through an innovative realization of Raman microscopy and image reconstruction. The method inherently allows to investigate large sample surfaces with no sample preparation requirements. A high flexibility of sample geometries, with the extension to map into sample depth non-destructively is possible. Its results are truly quantitative and in correspondence with established electron and x-ray techniques.

Mapping of crystallographic microstructure, while challenging at times, can be done today via many established methods through implementations in electron, x-ray or neutron microscopy. Nevertheless, it is known that polarized visible light and Raman microscopy is sensitive to crystallographic orientation changes in materials. In these cases, actual quantitative orientation mapping is very difficult to achieve due to obstacles requiring numerous measurements and the resolve of orientation ambiguities. This limits the output to only a small number of particular orientation cases, involving additional sample preparation steps and/or other supplemental knowledge [1]. 

To our best knowledge, no one has been successful in developing a stand-alone orientation mapping capability by Raman microscopy that is truly quantitative and generally applicable, until now.

By using a concept of ambiguity-free orientation determination reconstruction in combination with a novel polarized Raman microscopy approach, we present a fast and quantitative, single-acquisition Raman-based approach [2], which simultaneously registers multiple Raman spectra at different polarizations and allows for both 2D and 3D quantitative orientation mapping. The method applies to all Raman active materials independent of crystal symmetry and involves no sample preparation. Fundamentally inherent to our approach is the ability to investigate large sample areas in a short amount of time, while altogether not being restricted by any sample environment requirements or a sample’s geometrical extent.

Going beyond mere fundamental demonstrations of the approach, we have developed a commercially available solution, which enables routine quantitative Raman Imaging of Crystallographic Orientation (qRICO) for the non-expert user in any laboratory setting for simple and fast acquisition of orientation maps.

We will present an overview and detailed introduction into the fundamentals of the underlying approach and demonstrate qRICO’s performance on a selection of cases focussing on semiconductor research and photovoltaics applications (Figure 1), as well as polycrystalline ceramics.

Figure 1. Quantitative orientation mapping example of a poly-crystalline Si solar cell by (a) novel Raman microscopy qRICO and for reference in (b) standard EBSD.

References

[1] T. Schmid, N. Schäfer, S. Levcenko, T. Rissom, D. Abou-Ras, Sci. Rep. (2015), 5, 1.

[2] O. Ilchenko et al., Nat. Commun., DOI:10.1038/s41467-019-13504-8 (2019).