We describe a new method for removing thin, large area sheets of diamond from bulk or homoepitaxial diamond crystals. This method consists of an ion implantation step, followed by a selective etching procedure. High energy (4–5 MeV) implantation of carbon or oxygen ions creates a well-defined layer of damaged diamond that is buried at a controlled depth below the surface. For C implantations, this layer is graphitized by annealing in vacuum, and then etched in either an acid solution, or by heating at 550–600 °C in oxygen. This process successfully lifts off the diamond plate above the graphite layer. For O implantations of a suitable dose (3×1017 cm−2 or greater), the liftoff is achieved by annealing in vacuum or flowing oxygen. In this case, the O required for etching of the graphitic layer is also supplied internally by the implantation. This liftoff method, combined with well-established homoepitaxial growth processes, has considerable potential for the fabrication of large area single crystalline diamond sheets.

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Fast-neutron irradiation damage at 1.74 °K and its recovery to 100 °K have been investigated in Al and Au by means of residual electrical resistivity measurements. The effects of impurities, quenched-in vacancies, and dislocations were studied. It was found that the damage rate of Al was unchanged by impurity concentrations of less than 0.5 at. % and quenched-in vacancy concentrations of less than 0.002 at. %. Dislocation concentrations of ~2 × 1010/cm2 in Al and ~1011/cm2 in Au increased their damage rates by 35%and 50% respectively. Small amounts of impurity (~0.02 at. %) in Au increased its damage rate by 15% and suppressed the enhancement caused by deformation. The stage I recovery of Al and Au was only slightly increased by extra dislocations, but was increased considerably by quenched-in vacancies. An impurity concentration of ~0.5 at. % suppressed the stage I recovery of Al, but not that of Au. The results are interpreted in terms of channeling in Al and collision chains in Au.

The channelling of ions in crystals is described and its application to the study of a variety of lattice defects is outlined. Ions which are channelled along different crystallographic axes and planes interact with displaced atoms in distinctive ways, enabling the atomistic nature of lattice defects to be determined.Three main areas of study are considered. ( a ) The trapping of vacancies and self-interstitials by solute atoms and the ( b ) The displacement of host atoms from lattice sites (e.g. ion-induced amorphisa-(c) The relaxation and reconstruction of surfaces. identification of the resulting trapping configurations. tion of semiconductors).

The energy spectra of 1 MeV He+ ions backscattered from single crystals of Al alloys containing 0.09 at.% Mn, 0.09 at.% Zn, 0.08 at.% Ag, or 0.03 at.% Sn have been examined in different crystallographic directions. For the annealed crystals, the minimum yield of back-scattered He+ ions from Al atoms at 40 K in a [Formula: see text] direction was [Formula: see text], and the corresponding yield from Mn, Zn, or Ag impurity atoms was (χmin)i ≤ 0.06, indicating that at least 96% of these impurity atoms had replaced Al atoms at normal lattice sites. For the Al–0.03 at.% Sn alloy, the substitutional fraction of Sn atoms was only ~50% for a slowly cooled crystal, but was increased to ~90% by a rapid (water) quench from 600 °C. Irradiation of the crystals at 40–70 K with 0.3–1.0 MeV He+ ions to doses of 1015–1016/cm2 caused the Mn, Zn, and Ag atoms to be displaced from lattice sites by the trapping of self-interstitial Al atoms. From an analysis of [Formula: see text], [Formula: see text], {100}, and {111} channeling, it was shown that the trapping configuration was the [Formula: see text] dumbbell. Both the irradiation induced dechanneling and the displacement of these impurity atoms annealed out in recovery stage III, from 180–220 K, because of vacancy interstitial annihilation. The Sn atoms were not displaced appreciably by He+ ion irradiation at 40–70 K, but a displacement occurred during stage III recovery.