RADIATION-DAMAGE INDUCED BY MEV ALPHA-PARTICLES IN POLYCRYSTALLINE DIAMOND FILMS

Radiation damage induced by 2 MeV alpha particles in polycrystalline d iamond films has been studied as a function of the irradiation dose D (10(12)less than or equal to D less than or equal to 10(17) cm(-2)). T he films were characterized using Raman/photoluminescence spectroscopy and I(V,T) measurements. The results can be summarized as follows. In undoped samples the H3 luminescent center (N-V-N) is observed for D g reater than or equal to 10(14) cm(-2). The Raman diamond peak is broad ened and shifted to lower frequencies for D>10(15) cm(-2). No new grap hitic component is detected after irradiation. On the contrary graphit ic sp(2) defects are annealed by irradiation. For D=3X10(16) cm(-2) ne w Raman defect peaks are detected at 1496 and 1635 cm(-1). I(V,T) char acteristics remain unaffected for D less than or equal to 10(16) cm(-2 ). An increase in the conductivity is observed for D=3X10(16) cm(-2). At this dose we observe an activation energy of 0.4 eV and thermally s timulated currents related to defect levels at about 0.3 eV. A boron-d oped sample (100 Ohm cm) has been irradiated at 10(17) cm(-2) for comp arison. After irradiation the conductivity of this sample is reduced a nd the activation energy of the conductivity is also reduced. Less dam age is detected by Raman spectroscopy in the B-doped material. (C) 199 6 American Institute of Physics.