Shigemi Yugo

Generation of diamond nuclei by electric field in plasma chemical vapor deposition

Generation of diamond nuclei has been realized on a silicon mirror surface in plasma chemical vapor deposition. Prior to the normal diamond growth process, a predeposition process of several minutes duration was introduced in which a high methane fraction in the feed gas was used and in which a negative bias voltage was applied to the substrate. This resulted in an enormous enhancement of the generation of diamond nuclei. For the onset of diamond nucleation the minimum voltage was −70 V and the minimum methane fraction in the methane‐hydrogen feed gas was 5%. Density of a diamond nuclei as high as 1010/cm2 was attained with this method.

Nucleation mechanisms of diamond in plasma chemical vapor deposition

Abstract In a recent paper, we reported that a density of diamond nuclei as high as 10 10 cm −2 was attained on a mirror-polished silicon surface by pretreating the substrate surface in a hydrogen plasma containing a high concentration of methane and applying a negative bias. Under the most suitable conditions giving the highest density of diamond nuclei, i.e. pretreatment in hydrogen plasma with a methane content of 40% at a bias voltage of −100 V for 5 min, the obtained growth product was of star-ball shape consisting of amorphous carbon, silicon carbide and diamond. Amorphous carbon was found to be easily etched by the hydrogen plasma in the early stage of diamond growth after the pretreatment. Based on the above results, we present a model suggesting the mechanisms for the enhancement of diamond nucleation. The application of a negative bias collects carbon ions at higher rates onto the silicon surface, and increases their bond strength with the surface silicon owing to ion mixing. This enhances the formation of carbon clusters, overcoming re-evaporation and diffusion. The impinging energetic ions destroy the weak sp 2 structure and increase the sp 3 structure, leading to the formation of diamond nuclei precursors.

Electronic structures of B 2p and C 2p levels in boron-doped diamond films studied using soft x-ray absorption and emission spectroscopy

X-ray absorption (XAS) and emission (XES) spectroscopy near B K and C K edges have been performed on metallic (

Characteristics of the synthesis of β-SiC by the implantation of carbon ions into silicon

\ensuremath{\sim}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%

Impact excitation of the erbium‐related 1.54 μm luminescence peak in erbium‐doped InP

B, B-diamond) and semiconducting (

A new method for the generation of diamond nuclei by plasma CVD

\ensuremath{\sim}0.03\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%

Structure and annealing properties of silicon carbide thin layers formed by implantation of carbon ions in silicon

B and N, BN-diamond) doped diamond films. Both B K XAS and XES spectra show a metallic partial density of states (PDOS) with the Fermi energy of

Thermoelectric figure of merit of boron phosphide

185.3\phantom{\rule{0.3em}{0ex}}\mathrm{eV}

New method for selective growth of diamonds by microwave plasma chemical vapour deposition

, and there is no apparent boron-concentration dependence in contrast to the different electric property. In C K XAS spectrum of B-diamond, the impurity state ascribed to boron is clearly observed near the Fermi level. The Fermi energy is found to be almost same with the top of the valence band of nondoped diamond:

Formation mechanisms of diamond precursors during the nucleation process

{E}_{V}=283.9\phantom{\rule{0.3em}{0ex}}\mathrm{eV}