Light-ion-beam-induced annealing of implantation damage in diamond
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The removal of defects in diamond by light-ion bombardment has been studied by means of Rutherford backscattering spectroscopy (RBS) channeling techniques. The damage produced by 1X10 14 Sb ions cm" 2 at 300 keV (below the critical dose for graphitization) was observed to diminish by as much as 50% under bombardment with H and He ions. The ion-beam-induced annealing has been studied as a function of ion dose and incident angle (channeling and random). Although the data sets differ markedly, they nearly coincide when the dose is normalized to the energy deposited by elastic collisions in the damaged region. This may indicate that nuclear and not electronic collisions contribute primarily to the in situ annealing in a reasonably good insulator such as diamond.
I. INTRODUCTION Diamond is the thermodynamically unstable form of carbon, the stable one being graphite. The fact that carbon appears in two crystalline forms singles it out from the other group IV semiconductors (i.e., Si) and from most other crystals. This peculiarity of diamond also manifests itself in the annealing behavior of implantation-induced damage. In previous work1 we have shown that a critical damage concentration exists in implanted diamond, above which thermal annealing under normal pressure does not restore the diamond structure; instead, the damage layer converts into graphite. At an even higher dose, the implanted layer seems amorphous and is highly conductive. Graphitization can be avoided when implantation into heated diamond (T^, 600 °C) is carried out.2'3 In this case instantaneous annealing, assisted by the relatively low temperature and by the impact of the implanted ions, takes place. In the course of ion beam probing experiments on implanted diamond, we have observed a general disappearance of the damage, presumably as a result of the probing beam. This post implantation annealing, which is induced at room temperature by light ions ( H + and H e + ) , is the subject of the present work, in which the annealing is studied under a variety of beam conditions. It has been known for some time that ion beams can anneal radiation damage, even when the energy density of the ion beam is insufficient to significantly raise the substrate temperature.4"6 Williams has summarized the data 7 on the epitaxial regrowth of Si amorphized by ion implantation, caused by various ions at substrate temperatures well below the temperature required for solid phase epitaxial regrowth. Similar effects have been observed in other semiconductors in which shrinkage of the amorphous layer was induced mainly by heavy ions traversing the damage region.8 Little work was done on J. Mater. Res. 1 (3), May/Jun 1986 http://journals.cambridge.org
the annealing of damage initially below the amorphous level (as determined by Rutherford backscattering channeling experiments) caused by ion beams. Here defects are removed throughout the damaged volume during the annealing, in contrast to epitaxial regrowth from the bulk substrate crystal that pushes the crystallineamorphous interf
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