A stacking-fault based microscopic model for platelets in diamond

TL;DR

This paper introduces a microscopic model for diamond platelets based on metastable stacking faults involving $sp^2$ carbon layers, explaining various experimental signatures through ab initio calculations.

Contribution

The paper presents a novel stacking-fault based microscopic model for diamond platelets, supported by ab initio calculations, explaining their properties and formation mechanisms.

Findings

Model accounts for lattice displacement and asymmetry signatures.

Explains infrared absorption peak and luminescence lines.

Supports formation via natural shearing processes.

Abstract

We propose a new microscopic model for the $\{001\}$ planar defects in diamond commonly called platelets. This model is based on the formation of a metastable stacking fault, which can occur because of the ability of carbon to stabilize in different bonding configurations. In our model the core of the planar defect is basically a double layer of three-fold coordinated $sp^2$ carbon atoms embedded in the common $sp^3$ diamond structure. The properties of the model were determined using {\it ab initio} total energy calculations. All significant experimental signatures attributed to the platelets, namely, the lattice displacement along the $[001]$ direction, the asymmetry between the $[110]$ and the $[1\bar{1}0]$ directions, the infrared absorption peak $B^\prime$, and broad luminescence lines that indicate the introduction of levels in the band gap, are naturally accounted for in our model. The model is also very appealing from the point of view of kinetics, since naturally occurring shearing processes will lead to the formation of the metastable fault.