This paper reviews the growth of diamond by chemical vapour deposition (CVD). It includes the following seven parts: (1) Properties of diamond: this part briefly introduces the unique properties of diamond and their origin and lists some of the most common diamond applications. (2) Growth of diamond by CVD: this part reviews the history and the methods of growing CVD diamond. (3) Mechanisms of CVD diamond growth: this part discusses the current understanding on the growth of metastable diamond from the vapour phase. (4) Characterization of CVD diamond: we discuss the two most common techniques, Raman and XRD, which have been intensively employed for characterizing CVD diamond. (5) CVD diamond growth characteristics: this part demonstrates the characteristics of diamond nucleation and growth on various types of substrate materials. (6) Nanocrystalline diamond: in this section, we present an introduction to the growth mechanisms of nanocrystalline diamond and discuss their Raman features.This paper provides necessary information for those who are starting to work in the field of CVD diamond, as well as for those who need a relatively complete picture of the growth of CVD diamond.

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Diamond growth by chemical vapour deposition

A gas-phase purification method for raw nanotube material has been developed which incorporates a chlorine, water, and hydrogen chloride gas mixture to remove unwanted carbon. The evolved gases can be easily monitored by infrared spectroscopy to follow the cleaning process. The quality of the final material was verified by SEM (scanning electron microscopy), TGA (thermogravimetric analysis), and UV−vis (ultraviolet and visible absorption spectroscopy). The yield of ∼15 wt % indicates a uniquely selective carbon surface chemistry that prevents etching of the nanotubes, which are generally more reactive due to their larger curvature. Although the technique's usefulness for large-scale purification was not determined, the ability to purify single-wall nanotubes by a gas-phase method has been demonstrated, and a mechanism proposed.

Gas-Phase Purification of Single-Wall Carbon Nanotubes

Adv. Mater. 2010, 22, 843–847 2010 WILEY-VCH Verlag Gm A current trend in fluorescent probe technology is to expand the role of fluorophores that emit light in the far red and near infrared region for biomedical use. The negatively charged nitrogenvacancy defect center, (N-V) , in type Ib diamond is one of such fluorophores and has drawn much attention in recent years. The center exhibits several distinct features such as extended red emission at 700 nm, near-unity fluorescence quantum yield, and ultrahigh photostability (neither photobleaching nor photoblinking). These characteristics, along with the diverse surface functionalizability and non-toxic nature of the material, have made fluorescent nanodiamond (FND) a promising candidate among other conventional markers and labels, for example, organic dyes, fluorescent proteins, and quantum dots, for bioimaging applications. Despite the unique photophysical and biochemical properties of FND, the size is an important parameter to characterize. Decreasing the size, clearly, will increase the mobility of the fluorescent nanoprobe inside a cell, avoid altering the properties of targeted molecules, and enhance its translocation into cell nuclei. Additionally, particles of size in the range of 10 nm are more suitable for biolabeling and fluorescence resonance energy transfer (FRET) applications. However, so far the sizecontrolled production of FNDs has not yet been so well developed as that of other probes and scale-up synthesis of smaller and brighter FNDs remains a challenging task. In this communication, we report procedures of production and isolation of sub-20-nm FND particles utilizing He ion irradiation and differential centrifugation methods, and experiments demonstrating that they are useful as far-red fluorescent biolabels as well as FRET donors are presented. Table 1 compares the optical properties between (N-V) and two representative red and far-red fluorescent proteins. The in vivo structure of the latter protein is in form of tetramer and, therefore, has a size close to 10 nm. A simple calculation based on the molar extinction coefficient and the fluorescence quantum yield indicates that the brightness of a single (N-V) center is 2-fold as high as that of this far-red fluorescent protein, owing to the superb quantum yield of the atom-like fluorophore. Moreover, the (N-V) center fluoresces in the farther red region, where both autofluorescence and light scattering from the active biological environment are reduced to a greater extent. While compared to the infrared dye (such as IRDye-800CW in Table 1), the (N-V) center is a factor of 5 lower in brightness, this deficit can be readily compensated if each FND particle contains multiple (N-V) centers. It is the aim of this work to produce FNDs with a size comparable to those of far-red fluorescent proteins and concurrently containing as many (N-V) centers as possible. A previous experiment has shown that FNDs can be mass-produced with 40-keV Heþ irradiation of synthetic type Ib diamond nanocrystallites, followed by thermal annealing at 800 8C. For diamond powders with amedian size of 35 nm from a commercial source (MSY; Microdiamant), they usually have a broad size distribution and 10% of the particles are smaller than 15 nm. By optimizing the experimental parameters in differential centrifugation, we extracted sub-20-nm FNDs from the 35-nm ensembles after theHeþ irradiation andmulti-step centrifugation procedures. The sizes of these particles were finally characterized with dynamic light scattering (DLS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). As revealed by DLS (Fig. 1a), the average diameter of the smallest FNDs that we have been able to extract with use of a standard centrifuge (Model 3700; Kubota) is 11.5 nm, accompanied with a narrow size deviation from 10 to 14 nm. TEM and AFM (Figs. S1 and S2 in Supporting Information) also confirmed independently the size distribution centered in the range of 10 nm at the single particle level. To make a direct comparison of the optical properties between the 11-nm FNDs and monomeric red fluorescent proteins (recombinant DsRed; BioVision), we characterized both specimens in solution with fluorescence correlation spectroscopy (FCS).

Sub-20-nm fluorescent nanodiamonds as photostable biolabels and fluorescence resonance energy transfer donors.

Charged cluster model in the low pressure synthesis of diamond

Considering that diamond can grow without combination of pressure and heat, other effects in addition to ion impact thermal spikes effects must exist, which are ruling the growth of diamond and ta-C films (tetrahedral amorphous carbon). A newly proposed quantum electronic activation model for the diamond and diamond-like atomic rearrangement of carbon atoms appears to be confirmed by various elder and more recently published experimental results. It is based on various types of effects producing activation energy, before producing heat. Thus, it is possible to excite electron–hole pairs, which during their diffusion produce some transversal transient polarization, which under specific conditions can result in a new metastable atomic structure. This article focuses on published work on atomic rearrangements, which have been observed during annealing of diamond and some kinds of DLC (diamond-like carbon) coatings, such as a-C:H and a-CNx coatings. These atomic rearrangements were explained by using essentially Raman spectroscopy results, which are reviewed in this article, before being discussed with additional new proposed aspects on fundamentals to consider and which have been up dated in their interpretation. The considered atomic rearrangement model appears then also to be in agreement with some formerly discussed catalytic effects, which under specific conditions, favorize the growth of diamond and more diamond-like carbon films. It is expected that this new quantum electronic atomic rearrangement model will not be limited only to diamond, ta-C and DLC materials.

Quantum electronic mechanisms of atomic rearrangements during growth of hard carbon films

F2, H2O, and O2 etching rates of diamond and the effects of F2, HF and H2O on the molecular O2 etching of (110) diamond

Thermal activation of diamond growth in carbon-hydrogen-halogen systems

Mechanisms of diamond homoepitaxy by hot-filament CVD - Carbon-13 studies

A polished diamond (110) surface was observed to undergo surface rearrangement above ˜700 °C to a micro faceted diamond surface when in contact with a nickel film and in the presence of hydrogen. Formation of a graphitic layer at the diamond-nickel interface above 700 °C was observed in the absence of hydrogen. The presence of 0.1 Torr of hydrogen was shown to be sufficient to prevent graphite formation at the nickel-diamond interface.

C. J. Chu

Papers

F2, H2O, and O2 etching rates of diamond and the effects of F2, HF and H2O on the molecular O2 etching of (110) diamond

Thermal activation of diamond growth in carbon-hydrogen-halogen systems

Mechanisms of diamond homoepitaxy by hot-filament CVD - Carbon-13 studies

Nickel catalyzed reconstruction of a diamond (110) surface

Chlorine‐Activated Diamond Chemical Vapor Deposition.