Polycrystalline alumina (Al2O3) substrates, found in many electronic devices and proposed as dosemeters in emergency situations, were invstigated using a scanning electron microscope (SEM) equipped with cathodoluminescence (CL) and elemental analysis probes. The characteristics of the CL spectra, surface morphology, and impurity content of the Al2O3 substrates were examined and compared with those of single crystal dosimetry-grade Al2O3:C. Whereas the CL spectrum, measured from 250 to 800 nm, for the Al2O3:C, contained resolved bands located at ∼340 nm and at ∼410 nm, the spectrum measured with the Al2O3 substrate was signi ficantly broader, extending from ∼250 to ∼450 nm, and also included a narrow band at 695 nm. While it is likely that the accepted model of recombination at F+ (∼340 nm) and F (∼410 nm) in Al2O3:C also applies to the substrate, it is suggested that the presence of impurities within the alumina give rise to additional recombination centres. The 695 nm emission has been assigned to a Cr3+ ion impurity in previous work on alumina and a band indicated at ∼300 nm may be associated with Mg2+ or Ca2+, the presence of which was con firmed by elemental mapping. Comparison of the spatial distribution of CL with the surface morphology and elemental composition of the samples indicates that the components of the emission spectrum can be qualitatively correlated with impurity content and morphological features of the samples.
Bibliographical noteFunding Information:
This work is part of a PhD project at Durham University sponsored by Public Health England ( RF210130 ) with non-academic supervisors Dr Kai Rothkamm and Dr Rick Tanner.
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- Accident dosimetry
- Aluminium oxide