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

TL;DR

This paper investigates the mechanisms of ultra-fast laser-induced Frenkel defect formation in diamond, combining theoretical modeling and experimental validation to understand defect generation at the atomic level.

Contribution

It introduces a coupled rate equation model describing Frenkel defect creation via biexciton recombination during ultra-fast laser pulses in diamond.

Findings

Model agrees with experimental data

Reveals non-linearity of ~40 in defect generation

Identifies charge carrier dynamics as key process

Abstract

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