COMPRESSIVE STRESS-INDUCED FORMATION OF PREFERRED ORIENTATION IN GLASSY-CARBON FOLLOWING HIGH-DOSE C+ IMPLANTATION

It is well established that ion irradiation of glassy carbon with energetic ions leads to the formation of a dense amorphous surface layer. In the present work we show using cross-sectional TEM that oriented graphite-like regions are formed within the implanted layer of glassy carbon implanted with 50 keV C ions at high doses. The preferred orientation is such that the sp(2) bonded graphite-like sheets lie normal to the implanted surface. Stress measurements of the implanted material show the presence of a biaxial compressive stress. Thermodynamic calculations predict that a non-hydrostatic stress can result in preferred orientation in anisotropic materials such as graphite. The preferred orientation can therefore be explained in terms of the combined effects of the mobility introduced by the implanted ions and the anisotropic stress field.