Carder, D.A.; Markwitz, A. 2009 The formation of novel nanostructures using a combination of Si, N, C implantation into wafer silicon and glassy carbon on the SiC-Si3N4 tie-line. Lower Hutt, N.Z.: GNS Science. GNS Science report 2009/40 60 p.
Abstract: Novel surface nanostructures have been demonstrated following low energy ion implantation of carbon and nitrogen into wafer silicon. Combinations of carbon (12C) and nitrogen (14N) implantation doses were chosen to create materials with compositions on the SiC-S3N4 tie-line. Multiple implantation energies (up to 28 keV) were modelled to create thin films of the compounds in the first ~100-200 nm of the surface. Following ion implantation the surfaces were characterised using atomic force microscopy and were found to be free from nanostructures. Subsequently, electron beam annealing was used to heat the samples to temperatures of 1110oC and 1250oC for various durations. AFM analysis revealed nanostructuring of the annealed surfaces dependent on annealing conditions and nitrogen implantation fluence. At a nitrogen fluence content exceeding 30 at. % no significant nanostructures were present. However, evidence for nanostructure formation that is strongly dependent on annealing conditions is presented. The nanostructures for nitrogen content below 30 at. % were found to range from large (~350 nm) nanoboulders through to size distributions weighted towards 3-5 nm high structures. An alternative approach to nanostructure formation has been demonstrated for high nitrogen content implantations. A template of nanowhiskers was fabricated on the silicon surface prior to high dose implantation of carbon and nitrogen. The nanostructures are largely eroded by the implantation process to leave a general nano-roughening of the surface. However, it is shown that distinct nanostructures can be recovered through further annealing. It is demonstrated that following a two step electron beam annealing distinct nanostructures approaching the original distribution are observed. Finally, silicon (28Si) and nitrogen have been implanted into glassy carbon to form a silicon carbon nitride material. Following implantation Rutherford backscattering spectroscopy revealed a nitrogen content which was consistent with implantation fluence. The nitrogen content was not found to saturate at 26 at. % (reaching 30 at. %). This was attributed to the effect of the preceding silicon implantation and is consistent with previous published studies. (auth)