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Optical and Structural Changes of Fe Implanted Sapphire

Published online by Cambridge University Press:  17 March 2011

Carlos P. Marques
Affiliation:
ITN, Estrada Nacional 10, 2686-953 Sacavém, Portugal CFNUL, Av. Prof. Gama Pinto n° 2, 1649-003 Lisboa, Portugal
Eduardo J. Alves
Affiliation:
ITN, Estrada Nacional 10, 2686-953 Sacavém, Portugal CFNUL, Av. Prof. Gama Pinto n° 2, 1649-003 Lisboa, Portugal
Carl J. McHargue
Affiliation:
Center for Mat. Processing, Univ. of Tennessee, Knoxville, TN 37996-2350, USA
Maria F. da Silva
Affiliation:
ITN, Estrada Nacional 10, 2686-953 Sacavém, Portugal CFNUL, Av. Prof. Gama Pinto n° 2, 1649-003 Lisboa, Portugal
José C. Soares
Affiliation:
ITN, Estrada Nacional 10, 2686-953 Sacavém, Portugal CFNUL, Av. Prof. Gama Pinto n° 2, 1649-003 Lisboa, Portugal
Rosário Correia
Affiliation:
Universidade da Aveiro, Dept. Física, 3810-193 Aveiro, Portugal
Manuel J. Soares
Affiliation:
Universidade da Aveiro, Dept. Física, 3810-193 Aveiro, Portugal
Teresa Monteiro
Affiliation:
Universidade da Aveiro, Dept. Física, 3810-193 Aveiro, Portugal
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Abstract

Single crystalline colorless α-Al2O3 samples were implanted with several fluences of Fe+ ions in the range of 1×1016 to 5×1017 Fe+ cm-2 at room temperature. Optical absorption and luminescence measurements were carried out before and after annealing in reducing and oxidizing atmospheres. The structural changes were studied with RBS/channeling and x-ray diffraction. After implantation, the damage induces a brownish coloration in the samples for fluences below 2×1017 Fe+ cm-2. The optical spectra are characterized by an absorption band centered at 200 nm. This band is strongly reduced after annealing at 1100 °C in reducing atmosphere and a new well-defined band develops around 350 nm. This new band shifts to lower values with the implanted fluence, which is an indication of its correlation with the dimensions of the iron precipitates formed in the implanted region. The existence of these precipitates was confirmed by x-ray diffraction and TEM. The samples implanted with fluences above 1×1016 Fe+ cm-2 annealed in oxidizing atmosphere display different optical absorption spectra, with respect to those annealed in reducing atmosphere, characterized by an increase in the intensity of the peak at 200 nm. Luminescence measurements show the presence of F and F+ centers in the samples. The existence of these defects can be explained by the need of charge compensation and strain release due to the formation of mixed iron oxide or metallic precipitates.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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