Dg. Mcculloch et al., ION-BEAM MODIFICATION OF TETRAHEDRAL AMORPHOUS-CARBON - THE EFFECT OFIRRADIATION TEMPERATURE, DIAMOND AND RELATED MATERIALS, 6(11), 1997, pp. 1622-1628
The response of tetrahedral amorphous carbon to irradiation with 200 k
eV Xe+ ion irradiation at various temperatures is reported. The struct
ure of the tetrahedral amorphous carbon following ion irradiation is m
onitored iu-situ by electrical resistance measurements, and ex-situ by
Raman spectroscopy, electron energy loss spectroscopy and electron di
ffraction. It is found that the irradiation temperature strongly influ
ences the final state of the ion irradiated tetrahedral amorphous carb
on. For irradiation at room temperature and below, the ion beam transf
orms the material into a conducting amorphous carbon with an sp(2) fra
ction of about 0.6. The effect of elevated irradiation temperatures is
to increase the sp(2) fraction to about 0.8 at the highest doses and
to increase the degree of ordering. The ordering is distinctive in tha
t there is a high degree of in-plane disorder combined with a regular
stacking of the sp(2) bonded planes, The effect of temperature on the
ion beam induced transformation of tetrahedral amorphous carbon resemb
les that for the ion beam transformation of diamond for which low temp
erature irradiations produces a damaged amorphous structure, whereas f
or high temperatures a graphitic material is produced. (C) 1997 Elsevi
er Science S.A.