Microscopic processes during ultra-fast laser generation of Frenkel defects in diamond

Abstract

Engineering single atomic defects into wide bandgap materials has become an\nattractive field in recent years due to emerging applications such as\nsolid-state quantum bits and sensors. The simplest atomic-scale defect is the\nlattice vacancy which is often a constituent part of more complex defects such\nas the nitrogen-vacancy (NV) centre in diamond, therefore an understanding of\nthe formation mechanisms and precision engineering of vacancies is desirable.\nWe present a theoretical and experimental study into the ultra-fast laser\ngeneration of vacancy-interstitial pairs (Frenkel defects) in diamond. The\nprocess is described by a set of coupled rate equations of the pulsed laser\ninteraction with the material and of the non-equilibrium dynamics of charge\ncarriers during and in the wake of the pulse. We find that a model for Frenkel\ndefect generation via the recombination of a bound biexciton as the electron\nplasma cools provides good agreement with experimental data, reproducing an\neffective non-linearity of $\\sim$ 40 for Frenkel defect generation with respect\nto laser pulse energy.\n