The critical dose for graphitization of diamond as a result of ion implantation induced damage (boron and arsenic) and subsequent thermal annealing is determined by combining secondary ion mass spectroscopy measurements, chemical etching of the graphitized layer, and TRIM simulations. Li ions are implanted as a deep marker to accurately determine the position of the graphite/diamond interface. The damage density threshold, beyond which graphitization occurs upon annealing, is found to be 1022 vacancies/cm3. This value is checked against published data and is shown to be of general nature, independent of ion species or implantation energy.

Negatively charged nitrogen-vacancy (NV-) centers in diamond produced by ion implantation often show properties different from NVs created during the crystal growth. We observe that NVs created from nitrogen ion implantation at 30-300 keV show much shorter electron spin coherence time T-2 as compared to the "natural" NVs and about 20% of them show switching from NV-to NV0. We show that annealing the diamond at T=1200 degrees C substantially increases T2 and at the same time the fraction of NVs converting from NV-to NV0 is greatly reduced. (C) 2010 American Institute of Physics. [doi:10.1063/1.3527975]\u

The nitrogen-vacancy ͑NV͒ centers in diamond are amongst the most promising candidates for quantum information applications. Up to now the creation of such defects was highly probabilistic, requiring many copies of the nanodevice. Here we show that by employing a two step implantation process which includes low dose N 2 + molecular ion implantations followed by high dose C implantation can increase the generation efficiency of NV centers by over 50%. Moreover, we detected intrinsic 14 N concentration as low as 0.07 ppb by converting the nitrogen impurities into NV and then counting the single centers by using a confocal microscope.

Braunstein, G.; Muraviev, A.; Saxena, H.; Dhere, N.; Richter, V.; and Kalish, R., "p type doping of zinc oxide by arsenic ion implantation" (

Raman scattering (RS) spectra and current-voltage characteristics at room temperature were measured in six series of small samples fabricated by means of electron-beam lithography on the surface of a large size (5x5 mm) industrial monolayer graphene film. Samples were irradiated by different doses of C${}^+$ ion beam up to $10^{15}$ cm${}^{-2}$. It was observed that at the utmost degree of disorder, the Raman spectra lines disappear which is accompanied by the exponential increase of resistance and change in the current-voltage characteristics.These effects are explained by suggestion that highly disordered graphene film ceases to be a continuous and splits into separate fragments. The relationship between structure (intensity of RS lines) and sample resistance is defined. It is shown that the maximal resistance of the continuous film is of order of reciprocal value of the minimal graphene conductivity $\pi h/4e^2\approx 20$ kOhm.Comment: 5 pages, 5 eps figures. As accepted for publication in PR