Journal Published by Taylor & Francis Group
Editor's choice articles
Tailoring optical emission of silicon-vacancy centers in two-dimensional diamond nanosheets via a two-step oxidation approach
Incorporating two-dimensional (2D) diamond nanosheets with fluorescent color centers exhibits great potential in the application of quantum sensing. However, color centers always show poor optical emission in chemical-vapor-deposited (CVD) diamond nanomaterials. To address this issue, Si doped diamond/graphite hybrid films were successfully fabricated in microwave-plasma CVD device. The films consist of diamond-core/graphite-shell nanosheets with high amount of diamond nanocrystalline particles. Two post treatments of acid oxidation and annealing in air were used to tailor photoluminescence (PL) of silicon-vacancy (SiV) centers. The SiV centers in the oxidized samples exhibit small PL increase compared with the as-deposited samples with SiV PL quenching. It is found that the graphite phase is selectively etched away with the presence of nanocrystalline diamond particles during the treatment of acid oxidation while the nanocrystalline diamond particles are efficiently removed with the presence of graphite using the air annealing method. Based on this result, a two-step approach of acid oxidation followed by air annealing was conducted to etch the non-diamond phase, forming diamond nanosheets. The SiV centers exhibit significant PL enhancement with a maximum value of 28 folds, compared with the single-step oxidized samples. The Raman and XPS results reveal that such PL increase originates from direct bonding of oxygen on the carbon. Therefore, our work provides a feasible approach to prepare 2D diamond nanosheets with high-brightness color centers.
Volume 3, Issue 1 (2023)
CVD diamond: a review on options and reality
In the future, electronic parts will penetrate everything, generating a new and fast-growing pollution problem. Future devices therefore need to be environmentally friendly with strong recycling options. A paradigm change in semiconductor technology is predicted based on applications of better suited materials which can fulfil these criteria. Carbon based materials and here especially diamond are promising candidates. Bulk and surface properties of diamond are introduced in combination with applications in power electronics, quantum technology, bio-and electrochemistry and MEMS. Large amounts of diamond seeds and wafers will be required to approach commercial markets. Their availability in combination with quality and size as well as required energies for production are introduced. The production of CVD diamond is currently about 100–250 times more intense with respect to energy than Silicon. A problem which is addressed by use of new solid-sates microwave sources. The definition of “green diamond” is given taking into account requirements with respect to energy and methane/hydrogen production. A brief discussion and comparison of diamond global markets and related potentials in comparison to SiC and GaN is given.
deposition energy demand
Volume 3, Issue 1 (2023)
Insights on self-assembly of carbon in the processes of thermal transformations under high pressures
Peculiarities of the processes of self-assembly of carbon under pressure up to 8 GPa and temperatures up to 1600°C in pure carbon, hydrocarbon, fluorocarbon, organometallic systems and binary mixtures of all-carbon, hydrocarbon, and fluorocarbon compounds have been revealed in the course of studies of pressure and temperature-induced transformations of different carbon-containing systems. It was shown that the character of the processes of self-assembly of carbon in different systems is controlled in the first place by the mobility of carbon atoms. The low diffusion mobility of carbon atoms in a condensed state at temperatures below 2000° C leads to the fact that in pure carbon systems studied on the examples of fullerite C60 and closed polyhedral carbon nanoparticles, carbon self-organization can occur only due to processes associated with small movements of carbon atoms that ensure the formation of intermolecular bonds in cases of polymerization of C60 or the restructuring of the internal structure of a polyhedral particle, strictly limited to the confines of a single nanoparticle. In the hydrocarbon and fluorocarbon systems, the character of transformation changes drastically due to formation of volatile low-molecular hydrocarbon and fluorocarbon fractions, which ensure a high gas-phase or fluid mobility to carbon atoms. Studies of pressure and temperature-induced transformations of different hydrocarbon, fluorocarbon compounds and their homogeneous binary mixtures revealed a clear synergistic effect of fluorine and hydrogen on processes of carbonization, graphitization, and formation of diamond in these systems in relation to industrially significant reduction of p,T parameters for formation of graphite, diamond and increase in the content of nanosize diamond fractions in the products of transformations of binary mixtures in comparison with pure hydrocarbon and fluorocarbon compounds. Discovery of this synergistic effect opens new opportunities for synthesis of high-purity and doped ultranano-, nano-, submicro-, and micronsized diamonds with the specific properties for different applications in quantum physics and biomedicine. Studies of particularities of self-assembly of carbon in processes of thermal transformations of ferrocene at high pressures demonstrated the possibility of preparation of iron carbide nanoparticles encapsulated into carbon shells, Fe7C3@C and Fe3C@C, considered as perspective magneto-controlled platforms for different biomedical nanocomplexes.
pressure-temperature induced transformation
Volume 3, Issue 1 (2023)
Preparation of diamond on GaN using microwave plasma chemical vapor deposition with double-substrate structure
Combining diamond with GaN can significantly improve the heat dissipation performance of GaN-based devices. However, how to avoid the destructive damage to the GaN epi-layer caused by high-temperature hydrogen plasma during the diamond growth is still a problem. This study employed a Si transition layer and double-substrate structure microwave plasma chemical vapor deposition (MPCVD) to prepare diamond film on GaN epi-layer. The effects of double-substrate structure on the diamond growth were studied. The microwave plasma parameters of both single-substrate structure and double-substrate structure MPCVD diagnosed by emission spectra were comparatively investigated. It has been found that the microwave plasma energy of double-substrate structure MPCVD is relatively more concentrated and has higher radicals activity, which is beneficial to the diamond growth. The impacts of the Si transition layer on the diamond growth were also investigated. It demonstrates that the Si transition layer can effectively protect the GaN epi-layer from being etched by hydrogen plasma and improve the diamond growth. The relationship between the thickness of the Si transition layer and the diamond growth and the relationship between diamond film thickness and adhesion has been studied in detail.
Volume 3, Issue 1 (2023)
Orientated growth the 3D diamond/graphene hybrid arrays and the application in thermal interface materials
Diamond and graphene are considered to be one of the most promising thermal interface materials (TIMs) for electronic devices benefited from their highest thermal conductivity in the natural world. However, orientated fabrication of high thermal conductivity diamond and graphene hybrid arrays with three dimensions (3 D) thermal conductive networks are still problematic. Here, we used a unique one-step microwave plasma chemical vapor deposition, n-butylamine, as the liquid source to prepare a novel high thermal conductivity 3 D vertical diamond/graphene (VDG) hybrid arrays films. The orientated 3 D thermal conduction path of the VDG is regulated by the growth temperature, and the through-plane thermal conductivity value of the VDG700 films up to 97 W m−1 K−1. In the actual TIM performance measurement, the system cooling efficiency with our VDG as TIM is higher than the state-of-the-art commercial TIM, demonstrating the superior ability to solve the inter-facial heat transfer issues in electronic systems.
Volume 2, Issue 1 (2022)