Modification of single-crystal sapphire by ion implantation

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 1997-05, Vol.127, p.603-607
• Main Authors: Demaree, J.D., Kirkpatrick, S.R., Kirkpatrick, A.R., Hirvonen, J.K.
• Format: Article
• Language: English
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/S0168-583X(96)01128-7

Some studies have shown that single-crystal sapphire can exhibit a dramatic loss of compressive strength (over 90%) at high temperatures, limiting its use as a shatter-resistant optical window. Other studies have shown that the mechanical behavior of sapphire can be improved by ion implantation, hardening the near-surface region and introducing a compressive stress state, perhaps leading to an increase in the fracture toughness of the material. In this study, we have examined the extent to which sapphire can be implanted without severely degrading its optical quality by ion beam defect production. Optically-polished single-crystal c-axis sapphire was implanted with 150-keV Cr +, Ti +, and Si + ions to doses of (0.3−3.0) × 10 17 ions/cm 2 at both room temperature and at 800°C, to measure the optical effect of in situ annealing. Optical properties were measured by visible light transmission and Fourier transform infrared spectroscopy; the depth and composition of the implanted layer was characterized with Rutherford backscattering spectrometry; and the topography of the implanted surface was examined with photon tunneling microscopy.