A comparison of the structural changes and optical properties of LiNbO3, Al2O3 and ZnO after Er+ ion implantation

This paper reports on the structural as well as compositional changes of LiNbO3, Al2O3 and ZnO crystals, implanted with Er+ ions at 190 keV a with fluence of 1.0 × 1016 cm−2 into the <0001> crystallographic cuts. Post-implantation annealing at 1000 °C in oxygen atmosphere was also done. The chemical compositions and erbium concentration-depth profiles of implanted layers were studied by Rutherford Backscattering Spectrometry (RBS) and compared to SRIM simulations. The same value of the maximum erbium concentration (up to 2 at.%) was observed at a depth of about 40 nm for all crystals. The structural properties of the prepared layers were characterised by RBS/channelling. The relative numbers of disordered atoms in the prepared implanted layers were compared with each other and discussed for various crystals. It has been found that erbium is located in LiNbO3 and in Al2O3 preferably in interstitial positions, unlike ZnO, where the largest amount of erbium (about 83%) is placed in substitutional positions after the implantation. The erbium position in the host matrix was substantially influenced by the annealing procedure. In ZnO, after the annealing, the erbium amount in substitutional positions significantly decreased; in LiNbO3 and Al2O3 the increase of erbium in substitutional positions was observed simultaneously with the improvement of the quality of the reconstructed host matrix. Since we are interested in the relationship between structural changes and optical properties, the erbium luminescence properties were measured in the region of wavelength 1440–1650 nm for all crystals. After ion implantation LiNbO3 samples had zero luminescence intensity, while ZnO and Al2O3 samples had one significant luminescence band at 1537 and 1530 nm, respectively. The annealing improved the luminescent properties significantly in all investigated crystalline materials.