A. Laikhtman et al., Sensitivity of near-edge x-ray absorption fine structure spectroscopy to ion beam damage in diamond films, J APPL PHYS, 86(8), 1999, pp. 4192-4198
In the present work, we study the sensitivity of the near-edge x-ray absorp
tion fine structure (NEXAFS) spectroscopy to ion induced defects in polycry
stalline diamond films. The ion bombardment of hydrogenated films is perfor
med using 30 keV Xe+ ions at room temperature for doses ranging from 2 x 10
(13) ions/cm(2), producing local point defects, to 2 x 10(15) ions/cm(2), w
hich results in almost complete amorphization of the diamond surface. Auger
electron spectroscopy measurements are not sensitive to the modifications
induced by the lowest implantation dose. Whereas partial electron yield (PE
Y) NEXAFS measurements, applied in surface and bulk-sensitive modes, using
35, 15, and 8 eV secondary electrons, respectively, reveals the formation o
f a defective structure and gradual deterioration of diamond in the near-su
rface region. From PEY NEXAFS spectra measured using 15 eV secondary electr
ons, the position of C(1s) binding energy is measured. The x-ray photoelect
ron spectra of the samples were measured using an incident photon energy of
450 eV. It is found that the C(1s) binding energy in the implanted samples
has a positive shift of 0.6-1 eV, which is indicative of transformation of
diamond to disordered carbon. The high sensitivity of NEXAFS spectroscopy
to point defects induced by the low dose ion implantation was reflected by
a sharp reduction in the intensity of the diamond core exciton peak and by
the appearance of a new spectral feature in the pre-edge region, below the
C(1s)-pi* transition. Analysis of the NEXAFS spectra of ion implanted films
is performed on the basis of the electronic structure of diamond. (C) 1999
American Institute of Physics. [S0021-8979(99)02220-3].