Kazuhito Nishimura

BLUE AND GREEN CATHODOLUMINESCENCE OF SYNTHESIZED DIAMOND FILMS FORMED BY PLASMA-ASSISTED CHEMICAL VAPOUR DEPOSITION.

Cathodoluminescence study of synthesized diamond films formed by magneto-microwave plasma CVD and usual microwave plasma CVD has been carried out for the first time. The visible luminescence spectra of these diamond films show that peaks occur at different energies between 2.4–2.8 eV (green to purple-blue by visual inspection), depending on the deposition conditions. These spectra can be classified into so-called band A luminescence commonly observed in all types of bulk diamond. The growth sectors of {100} (bright visible emission) and {111} (dark) can be differentiated by the intensity of luminescence. These features are analogous to the luminescent properties of high-pressure synthesized diamond.

Origin of Field Emission from a Nano-Diamond/Carbon Nanowall Electron Emitter

The origin of field emission from a specific nano-diamond/carbon nanowall (ND/CNW) electron emitter, which has high and stable field emission characteristics, was examined by field emission spectromicroscopy and scanning electron microscopy. It was found that graphite sticks are present on the field emission sites of the films. Energy distribution curves of electrons field-emitted from the specified sites have the same features as those field-emitted from a metallic substance (graphite). Thus, it was concluded that graphite sticks present on the ND/CNW film are responsible for the field emission.

Effect of Hydrogen Plasma Treatment on Implantation Damage in Diamond Films Grown by Chemical Vapour Deposition

Radiation damage in chemical vapour deposited (CVD) diamond produced by the implantation of 10-keV nitrogen ions has been studied using electron energy loss spectroscopy (EELS) and cathodoluminescence. Thermal annealing and a hydrogen plasma treatment have been employed to anneal out the implantation damage. Graphitization of ion implanted CVD diamond was observed after subsequent thermal annealing. On the other hand, similar EELS spectra to that of as-grown diamond have been obtained from ion-implanted CVD diamond after hydrogen plasma treatment.

Study of impurities in CVD diamond using cathodoluminescence

Nitrogen ions were implanted into diamond films formed by microwave plasma CVD. A color cathodoluminescence (CL) system were used to investigate the emission centers of as implanted and the subsequent annealed films. A zero-phono-line (ZPL) from the implanted N+ was observed at 3.19 eV. After annealing, a ZPL at 2.16 eV and a strong emission center in the violet region with a ZPL at 3.19 eV and phonon replicas were observed. The color CL images of the annealed films show that an orange-red color emission comes only from the {100} sectors because of the difference in crystal quality between the {100} and {111} sectors.

Crystallinity and strength of diamond bombarded with low energy ion beams

Abstract In order to improve the performance of diamond tools formed or sharpened with Ar ions, we have used RHEED to investigate the crystallinity of diamond specimens machined with argon ions of 0.4–2.0 keV and processed with hydrogen plasma (ions and atoms) at 800–850° C under various conditions. Moreover, the microstrength of diamond specimens machined with Ar ions and processed with hydrogen plasma has also been investigated by Hertz indentation. The damaged layer of the diamond specimen caused by Ar ion bombardment can be removed by processing with hydrogen plasma. Moreover, the microstrength of a diamond specimen prefinished by conventional mechanical lapping (39 GPa) is decreased to 34 GPa by bombardment with argon ions. However, that is increased to 47 GPa by processing with hydrogen plasma.

Observing diamond defects with an analytical color-fluorescence electron microscope

Vie have developed an analytical color fluorescence electron microscope (ACFEM) which is now being studied as a possible tool for evaluating diamonds. The ACFEM permits observation using colors corresponding to cathodoluminescence (CL) wavelengths in the visible region (400700nm) to distinguish the type size and distribution of emission centers and emission bands of diamonds. The ACFEM is an effective tool for determing the conditions used for synthesizing chemical vapor deposition (CVD) diamonds and is far superior to xpS and SIMS as a tool for analyzing dopants. 1.