The defect structure of sapphire produced by implantation of Zr and Zr plus O: threshold fluence for amorphization and optical properties

Abstract

Zirconium implantation‐induced amorphization has been investigated with Rutherford back scattering spectrometry along a channeling direction (RBS‐C) using 2 MeV He+. Ion implantation was carried out at the energy of 175 keV, with fluences of 2×1015 to 2×1016 Zr+/cm2 at room temperatures. The critical amorphization fluence at room temperature was determined as ∼1.5×1016 Zr+/cm2 corresponding to ∼ 40 dpa; ∼2.7% peak Zr‐concentration) which is a lower damage energy than that reported for implantation with ions of similar mass and energy. The effect of post implantation of oxygen into a pre‐implanted sample (with zirconium) was investigated. The RBS results show that oxygen implantation in a crystalline sample increases the damage only slightly and slightly broadens the Zr profile. For the fluences above thresh‐old for amorphization, post implantation by oxygen has very little effect on the residual damage or on the Zr distribution. The presence of both F and F+ centers were indicated by optical absorption (OA) measurements. The OA spectra show the concentration of F and F+ centers increases with increasing fluence with some changes resulting from oxygen implantation of a pre‐zirconium‐implanted sapphire. This alters the relative concentrations of F and F+ centers. The F‐type center concentrations for the samples were calculated using Smakula's equation. Photoluminescence (PL) at an excitation of 255 nm confirms the presence of both F and F+ centers with emission peaks at about 420 and 325 nm respectively. The PL spectra suggest that oxygen implantation decrease the concentration of the both species, consistent with the OA results (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)