Electrical property of high-fluence metal ion implanted sapphire and its thermal annealing effects

Iron ions were implanted to single crystal alpha-alumina (0 0 0 1) surface up to 1.0 x 10(18) ions/cm(2) at 380 keV. Postimplantation electrical-resistance measurement was carried out from room temperature to 5 K. The resistance of the specimen implanted with 1.0 x 10(17) ions/cm(2) was 1.13 x 10(9) Omega at room temperature. It increased with decreasing temperature to 3.33 x 10(11) Omega at 77 K. On the other hand, the resistances of the specimens with 4.0 x 10(17) ions/cm(2) and 1.0 x 10(18) ions/cm(2) were 3.6 x 10(2) Omega and 5.5 Omega in room temperature, respectively. They decreased slightly with decreasing temperature to 3.0 x 10(2) Omega and 4.1 Omega at 5 K. These high-fluence implanted specimens were annealed at 1073 K for 12 h in air. Iron atom migration toward the surface due to thermal annealing were also investigated by Rutherford's Backscattering Spectroscopy (RBS). An island-like feature appeared on the surface of the specimen, which was observed by Atomic Force Microscopy (AFM). (C) 1998 Elsevier Science B.V. All rights reserved.