We describe monocrystalline graphitic films, which are a few atoms thick but are nonetheless stable under ambient conditions, metallic, and of remarkably high quality. The films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands, and they exhibit a strong ambipolar electric field effect such that electrons and holes in concentrations up to 10 13 per square centimeter and with room-temperature mobilities of ∼10,000 square centimeters per volt-second can be induced by applying gate voltage.

http://science.sciencemag.org/content/sci/306/5696/666.full.pdf

Electric Field Effect in Atomically Thin Carbon Films

J. Y. Tsao,* S. Chowdhury, M. A. Hollis,* D. Jena, N. M. Johnson, K. A. Jones, R. J. Kaplar,* S. Rajan, C. G. Van de Walle, E. Bellotti, C. L. Chua, R. Collazo, M. E. Coltrin, J. A. Cooper, K. R. Evans, S. Graham, T. A. Grotjohn, E. R. Heller, M. Higashiwaki, M. S. Islam, P. W. Juodawlkis, M. A. Khan, A. D. Koehler, J. H. Leach, U. K. Mishra, R. J. Nemanich, R. C. N. Pilawa-Podgurski, J. B. Shealy, Z. Sitar, M. J. Tadjer, A. F. Witulski, M. Wraback, and J. A. Simmons

/pdf/ultrawide-bandgap-semiconductors-research-opportunities-and-49ev1zu2ym.pdf

Ultrawide-Bandgap Semiconductors: Research Opportunities and Challenges

Conducting, boron doped diamond (BDD), in addition to its superior material properties, offers several notable attributes to the electrochemist making it an intriguing material for electrochemical research. These include the widest solvent window of all electrode materials; low background and capacitive currents; reduced fouling compared to other electrodes and; the ability to withstand extreme potentials, corrosive and high temperature/pressure environments. However, BDD is not your typical electrode material, it is a semi-conductor doped degenerately with boron to present semi-metallic characteristics. Input from materials scientists, chemists and physicists has been required to aid understanding of how to work with this material from an electrochemical viewpoint and improve electrode quality. Importantly, depending on how the BDD has been grown and then subsequently treated, prior to electrochemical measurement, the resulting material properties can vary quite significantly from one electrode to the next. This likely explains the variability seen by different researchers working on the same experimental systems. The aim of this "protocols" article is not to provide a state-of-the-art review of diamond electrochemistry, suitable references are provided to the interested reader, but instead serves as a reference point for any researcher wishing to commence work with diamond electrodes and interpret electrochemical data. It provides information on how best to characterise the material properties of the electrode before use and outlines the interplay between boron dopant density, non-diamond-carbon content, grain morphology, surface chemistry and redox couple identity. All should ideally be considered when interpretating electrochemical data arising from the diamond electrode. This will aid the reader in making meaningful comparisons between data obtained by different researchers using different diamond electrodes. The guide also aims to help educate the researcher in choosing which form of BDD is best suited to their research application.

A practical guide to using boron doped diamond in electrochemical research.

In this paper we review and provide an overview to the understanding of the chemical vapor deposition (CVD) of diamond materials with a particular focus on the commonly used microwave plasma-activated chemical vapor deposition (MPCVD). The major topics covered are experimental measurements in situ to diamond CVD reactors, and MPCVD in particular, coupled with models of the gas phase chemical and plasma kinetics to provide insight into the distribution of critical chemical species throughout the reactor, followed by a discussion of the surface chemical process involved in diamond growth.

/pdf/understanding-the-chemical-vapor-deposition-of-diamond-4150z5ly79.pdf

Understanding the chemical vapor deposition of diamond: recent progress.

Electrochemical reactions typically involve electron transfer between an electrode and a dissolved chemical species at a solid-electrode/liquid-electrolyte interface. Three broad classes of electrochemical applications may be identified: (1) synthesis (or destruction), in which an applied potential is used to bring about a desired chemical oxidation or reduction reaction; (2) analysis, in which the current/potential characteristics of an electrode are used to determine the type and concentration of a species; and (3) power generation. These broad types of applications require stable, conductive, chemically robust, and economical electrodes. Diamond electrodes, fabricated by chemical vapor deposition, provide electrochemists with an entirely new type of carbon electrode that meets these requirements for a wide range of applications.The first reports of electrochemical studies using diamond were in the mid-1980s. During the past several years, the field has attracted increasing attention. This review summarizes the electrochemical properties of diamond that make it a unique electrode material and that distinguish it from conventional carbon electrodes.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0883769400029389

Applications of Diamond Thin Films in Electrochemistry

Characterization of single-crystal diamond grown by chemical vapour deposition processes

Cvd diamond growth mechanisms as identified by surface-topography

Epitaxial, boron-doped diamond films were grown by hot-filament-assisted chemical vapour deposition (CVD) on (100) and (110) natural diamond substrates. Resistivity measurements for 10 K<T<500 K showed a clear transition from band to hopping conduction upon lowering of temperature. In the band conduction regime, the (100) films had higher conductivity than the (110) samples. The reverse was found in the hopping regime. This is explained by the difference in crystal growth mechanisms, leading to higher boron concentrations and lower carrier mobilities for (110) samples than for (100) oriented films. Hall effect measurements were performed for the most lightly doped (100) film at a boron level of 2.7*1018 cm-3 in the band conduction region up to 750 K. A mobility maximum of mu H=590 cm2 V-1 s-1 at 295 K was found, and the compensation ratio was determined to be smaller than 0.02. Some preliminary values for the Hall effective mass of valence band holes are given.

https://iopscience.iop.org/article/10.1088/0953-8984/4/36/011/pdf

Electrical conduction in homoepitaxial, boron-doped diamond films

https://repository.ubn.ru.nl/bitstream/handle/2066/112640/112640.pdf

G. Janssen

Papers

Characterization of single-crystal diamond grown by chemical vapour deposition processes

Cvd diamond growth mechanisms as identified by surface-topography

Electrical conduction in homoepitaxial, boron-doped diamond films

Controlled deposition of diamond from an acetylene-oxygen combustion flame

Mosaic Growth of Diamond