The pressure-temperature phase and transformation diagram for carbon; updated through 1994

Diamond cold cathodes have been formed by fabricating mesa-etched diodes using carbon ion implantation into p-type diamond substrates. When these diodes are forward biased, current is emitted into vacuum. The cathode efficiency (emitted current divided by diode current) varies from 2*10/sup -4/ to 1*10/sup -10/ and increases with the addition of 10/sup -2/-torr partial pressure of O/sub 2/ into the vacuum system. Current densities of 0.1 to 1 A-cm/sup -2/ are estimated for a diode current of 10 mA. This compares favorably with Si cold cathodes (not coated with Cs), which have efficiencies of approximately 2*10/sup -5/ and current densities of approximately 2*10/sup -2/ A-cm/sup -2/. It is believed that higher current densities and efficiencies can be obtained with more efficient cathode designs and an ultrahigh-vacuum environment. >

Diamond cold cathode

Effective utilization of methane remains one of the long-standing problems in catalysis. Over the past several years, various routes, both direct and indirect, have been considered for the conversion of methane to value-added products such as higher hydrocarbons and oxygenates. This review will focus on the range of issues dealing with thermal and catalytic decomposition of methane that have been addressed in the last few years. Surface science studies (molecular beam methods and elevated-pressure reaction studies) involving methane activation on model catalyst systems are extensively reviewed. These studies have contributed significantly to our understanding of the fundamental dynamics of methane decomposition. Various aspects of the nonoxidative methane to higher hydrocarbon conversion processes such as high-temperature coupling and two-step low-temperature methane homologation have been discussed. Decomposition of methane results in the production of COx-free hydrogen (which is of great interest to sta...

Nonoxidative Activation of Methane

http://navier.engr.colostate.edu/pubs/DiamRelatedMater_4_1173_1995.pdf

Studies on nucleation process in diamond CVD: an overview of recent developments

Ion‐assisted pulsed laser deposition has been used to produce films containing ≳85% sp3‐bonded cubic boron nitride (c‐BN) By ablating from a target of hexagonal boron nitride (h‐BN), BN films have been deposited on heated (50–800 °C) Si(100) surfaces The growing films are irradiated with ions from a broad beam ion source operated with Ar and N2 source gasses Successful c‐BN synthesis has been confirmed by Fourier transform infrared (FTIR) spectroscopy, high‐resolution transmission electron microscopy (TEM), selected‐area electron diffraction, electron energy‐loss spectroscopy, and x‐ray diffraction The films are polycrystalline and show grain sizes up to 300 A In addition, Rutherford backscattering, elastic recoil detection, and Auger electron spectroscopies have been used to further characterize the samples The effects of varying ion current density, substrate growth temperature, growth time, and ion energy have been investigated It is found that stoichiometric films with a high c‐BN percentage ca

Ion-assisted pulsed laser deposition of cubic boron nitride films

This book covers the following topics: Vapor phase diamonds; General, theory, modeling; Natural and synthetic HP/HT diamond; Gas phase and surface measurements; Gas phase and surface chemistry; Properties: Mechanical, chemical, thermal; Properties: Electrical; Diamond-like materials; and Cubic boron nitride.

New diamond science and technology

The seeding for large‐area mosaic diamond films approaching single‐crystal quality is described. The technique includes patterned etching of relief structures in Si substrates, deposition from a slurry and orientation of macroscopic diamond seed crystals in the structures, and chemical vapor deposition overgrowth of the diamond seeds to form a continuous film. The film comprises ∼100 μm single crystals, which are separated by low‐angle grain boundaries of a few degrees or less. We believe that these low‐angle grain boundaries will not affect the electrical properties of majority‐carrier devices.

J.E. Butler

Papers

New diamond science and technology

Large‐area mosaic diamond films approaching single‐crystal quality