Aluminum and aluminum nitride formation in sapphire by ion beam synthesis

The ion beam synthesis of Al layers in c-plane sapphire by a single high-do se, high-temperature Al implantation step is studied using various methods. At sufficiently high doses, buried single-crystalline Al layers are obtain ed. XRD pole-figure measurements and transmission electron diffraction reve al an epitaxial relationship with the sapphire matrix according to [1 (1) o ver bar 0](Al)\\[1 (1) over bar 00]Al2O3 and (111)(Al)\\(0001)Al2O3. The la yers exhibit smooth and atomically sharp interfaces in HREM studies. For lo w doses, indications are found that in situ ripening processes lead to self -organized arrangements of precipitates in chains parallel to the surface, and that the coalescence of precipitates is affected by the internal twin-s tructure of isolated Al precipitates. In addition, the transformation of th e buried Al layer into a textured polycrystalline AIN layer by a subsequent high-dose nitrogen implantation is investigated. (C) 2000 Elsevier Science B.V. All rights reserved.