Physical property change of concurrently neutron-irradiated CVD-diamond, silicon and silicon carbide

Diamond films on single-crystal silicon or polycrystalline silicon carbide substrates were neutron irradiated up to a fluence of 5.3×1024 n/m2 (En>0.1 MeV) at 380 °C. After irradiation, changes in X-ray diffraction, Raman spectra and microstructure were observed. Some specimens were further annealed up to 1500 °C, and changes in these properties were measured. The lattice parameters expanded by 0.76%, 0.60% and 0.005% in diamond, silicon carbide and silicon, respectively. The Raman peak of diamond at 1335 cm−1 was weakened and shifted 30 cm−1 toward lower wave numbers and was asymmetric after irradiation, but after annealing up to 1500 °C a relatively large peak at 1331 cm−1 was observed. Raman peaks corresponding to sp2 clusters were also observed after irradiation and post-irradiation annealing at 1500 °C. The lattice parameter of diamond started to decrease at around the irradiation temperature and linearly decreased up to 1200 °C, but not fully recovered after annealing at 1300 °C. Partial amorphization was observed only in irradiated Si.