Modification of the structure of diamond with MeV ion implantation

TL;DR

This study combines experiments and simulations to understand how MeV ion implantation alters the structural and mechanical properties of single-crystal diamond, providing a comprehensive model and insights into damage effects and thermal annealing.

Contribution

It introduces a combined experimental and numerical approach to model damage-induced property changes in diamond and refines the method to determine the graphitization threshold.

Findings

Validated models with X-ray diffraction and profilometry data

Quantified surface swelling and internal strain due to ion damage

Provided insights into thermal annealing effects on damaged diamond

Abstract

We present experimental results and numerical simulations to investigate the modification of structural-mechanical properties of ion-implanted single-crystal diamond. A phenomenological model is used to derive an analytical expression for the variation of mass density and elastic properties as a function of damage density in the crystal. These relations are applied together with SRIM Monte Carlo simulations to set up Finite Element simulations for the determination of internal strains and surface deformation of MeV-ion-implanted diamond samples. The results are validated through comparison with high resolution X-ray diffraction and white-light interferometric profilometry experiments. The former are carried out on 180 keV B implanted diamond samples, to determine the induced structural variation, in terms of lattice spacing and disorder, whilst the latter are performed on 1.8 MeV He implanted diamond samples to measure surface swelling. The effect of thermal processing on the evolution of the structural-mechanical properties of damaged diamond is also evaluated by performing the same profilometric measurements after annealing at 1000 {\deg}C, and modeling the obtained trends with a suitably modified analytical model. The results allow the development of a coherent model describing the effects of MeV-ion-induced damage on the structural-mechanical properties of single-crystal diamond. In particular, we suggest a more reliable method to determine the so-called diamond "graphitization threshold" for the considered implantation type.