Diamond is a material with superlative properties in terms of carrier mobilities and device characteristics for high power electronics applications. Although p‐type diamond is routinely available using boron, n‐type material via impurity doping during the growth of diamond has historically been limited in success, partly because nitrogen is a hyper‐deep donor, but compounded by the compact lattice leading to low solubilities for alternative species. Implantation doping is often hampered by persistent residual damage leading to significant levels of compensation and the formation of dopant complexes with lattice vacancies. Experiment has been augmented by the application of quantum‐chemical methods to assess the likely properties should specific impurities or impurity complexes be realisable in real materials. The review outlines many of the doping strategies explored for diamond, including simple impurity doping and co‐doping. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Noble-gas species are important impurities in the geological analysis of natural diamond and are also used in ion implantation on the basis of chemical inertness. We present the results of density functional simulations of noble-gas atoms in diamond. We show that interstitial species are relatively mobile under geological conditions but require annealing above ϳ700 K for laboratory-based experiments. In addition, with the exception of interstitial helium and neon, the noble-gas atoms are able to react chemically with the diamond due to the compact diamond lattice. This is of particular significance in terms of ion implanted material where noble-gas species trapped in lattice vacancies are electrically active and stable to high temperatures.

Doping of diamond using multi‐component, multi‐species structures has been modelled using density functional methods. We find that few combinations of impurities yield donor levels shallower than phosphorus. Complexes involving impurities from the second or lower rows of the periodic table are unbound, and those involving the soluble element nitrogen can often be arranged in passive or even compensating geometries. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Phosphorus, the current standard n-type dopant in diamond, has been correlated with isotropic, trigonal and tetragonal paramagnetic centres, suggesting that it may undergo a symmetry lowering distortion, perhaps of a Jahn–Teller type. We present first-principles calculations for examining the energetics of various sub-group symmetries of the on-site, tetrahedral donor, and show that C2v, C3v and D2d conformations reduce the total energy and conform to the Jahn–Teller theorem. We also present a qualitative explanation of the resulting quantum-mechanical states. The small amount of energy saved by the distortion may indicate a dynamic Jahn–Teller effect.