Diamond polytypes and their vibrational spectra

Abstract

A series of diamond polytype structures are described and their IR and Raman vibrational modes predicted. The diamond polytypes are analogous to the well-known silicon carbide polytypes. The intermediate 6H diamond polytype was recently identified by single crystal electron diffraction of vapor precipitated diamond powder. In addition, end member polytypes of 3C (cubic diamond) and 2H diamond (hexagonal lonsdaleite) have been previously established, and polytypes such as 4H, 8H, 15R, and 21R diamond are predicted, but may be difficult to isolate and identify. The various diamond polytype structures differ only in the stacking sequences of identical puckered hexagonal carbon layers. These identical carbon layers lie parallel to the cubic 3C {111} and the hexagonal 2H {001} planes. A new method for uniquely labeling the structural layers in the polytype stacking sequences is presented. Factor group analysis was used to determine the IR and Raman selection rules for five diamond polytypes with structures intermediate between those of end members diamond and lonsdaleite. Brillouin zone folding techniques were used to determine band positions, in analogy with analyses of SiC polytypes discussed in the literature. The results predict that (i) all diamond polytypes are Raman active, (ii) limiting polytypes 3C and 2H are not IR active, and (iii) polytypes 4H, 6H, 8H, 15R, and 21R have IR active modes.

Diamond homoepitaxy by chemical vapor deposition

“…0.1 gm, in size by electron diffraction [29,30]. In this paper, we report X-ray diffraction data for homoepitaxial It is worth mentioning that the substrate lla type films which indicate distortion of the cubic diamond crystal plate with (001) top surface had the side surfaces structure.…”

Carbon structures in silicon carbide derived carbon

“…These two types are considered to be the parent diamond structures because any other diamond polytypes are based on combination of layer sequences of 2H or 3C diamond. Other diamond polytypes such as hexagonal 4H, 6H, 8H and 10H and rhombohedral 15R and 21R diamond phases have been theoretically predicted [5,6] and some of them experimentally confirmed (4H, 6H and 8H [7][8][9] 9R and 15R [10,11]). …”

Laser‐Induced Direct Lithography for Patterning of Carbon with sp3 and sp2 Hybridization

“…Hexagonal diamond is usually formed under conditions that require rapid growth. [20,22] In addition, as can be seen in the carbon phase diagram, there are regions where cubic and hexagonal diamond co-exist. [23] Based on the d = 2.06 spacing of the main sp 3 diffraction ring, we assigned the cubic diamond form to our sample.…”