Neutron irradiation and annealing of ¹⁰B doped chemical vapor deposited diamond films

Abstract

10B doped diamond films grown by hot filament chemical vapor deposition were neutron irradiated at moderately high fluence levels. The as-irradiated and annealed samples, along with an unirradiated sample, were analyzed using Raman spectroscopy and x-ray diffraction. It was found that a non-diamond amorphous phase was formed on irradiation. This phase transformed back to diamond on annealing. No graphite formation was observed. A comparison with nanodiamond powder was made. A similarity between irradiated diamond films and nanocrystalline diamond powder is discussed.

Contribution of Functional Groups to the Raman Spectrum of Nanodiamond Powders

“…This unusual temperature behavior contradicts several assignments of the 1640 cm −1 peak in the Raman spectrum of ND proposed in literature suggesting that it cannot originate from: surface sp 2 carbon, , surface amorphous carbon, mixed sp 2 /sp 3 carbon, or split interstitial defects inside the diamond core of ND, as they should all result in small, linear and reversible changes within the temperature range 25−300 °C. Although it was shown before that split interstitial defects in bulk diamond can be “healed” by annealing in an inert atmosphere, it happens at temperatures much higher than 300 °C.…”

“…Thus, there is no general “Raman spectrum of ND”, as it varies for different ND grades. Furthermore, while the peak at 1590 cm −1 in UD50 can be identified as G-band of graphitic carbon, the assignment of the peak at 1640 cm −1 observed in UD90 and UD90OxHCl as well as in many other ND samples reported in the literature ,,, is not straightforward.…”

Probing the Nanostructure of Neutron-Irradiated Diamond Using Raman Spectroscopy

“…Earlier, similar Raman spectra in RD diamonds were recorded by other scientists in CVD diamonds irradiated by fast neutrons [19,40] or implanted with high-energy ions [13,14,21,36]. In Reference [41], the authors concluded that the match between the Raman spectra of diamonds implanted with MeV helium ions and the results of DOS calculations for «amorphous diamond» [42], i.e., for clusters of nanostructured carbon with sp 3 ordering without long-range order, provides evidence for complete amorphization of diamond under ion implantation.…”

High-temperature neutron irradiation effects on CVD-diamond, silicon and silicon carbide

“…Khasawinah et al observed resemble peak shift of this diamond peak for 10 B doped diamond after neutron irradiation in the order of 10 24 n/ m 2 (E n > 0.1 MeV) [19]. Compare with the lower temperature irradiation case, the amount of shift and deformation of peak shape was small, indicating less damage.…”

“…No clear peaks at around 1580-1620 cm À1 corresponding graphite sp 2 was observed, thus degree of broken sp 3 bonding is less significant at higher temperature irradiation. In the case of lower temperature irradiation, large shift and deformation of peak shape coupled with the presence of a characteristic peak at about 1600 cm À1 indicating presence of sp 2 cluster [19][20][21].…”