Twins and dark features in MPCVD diamond films

Abstract

In this study, diamond films were prepared by Microwave Plasma Chemical Vapor Deposition (MPCVD). The twins, dark features, pores, and their surface relationships were investigated, with a focus on the crystallographic transition within fivefold twins, the growth characteristics of distinct film regions and dark features, and the mechanisms of pore formation. The samples were characterized using SEM, XRD, Raman spectroscopy, EBSD, Optical microscopy, and Laser confocal microscopy, complemented by first-principles calculations and molecular dynamics simulations.

It is demonstrated that Σ3 twins, fivefold twins, and parallel twins all constitute Σ3 twin boundaries, among other types of twin boundaries, and ∑3 twins, fivefold twins and parallel twins are contact twins. It is revealed that the transformation of the crystal planes is due to energy fluctuations, and the results show that the dark features are mainly composed of growth pores, and the regions with more dark features are often accompanied by a greater number of pores. In addition, it is revealed that the growth pores are mainly formed under the influence of twins, which may lead to different growth rates of crystal planes and atomic misalignment, both of which may promote the formation of growth pores, but the first formation mechanism is predominant.