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Abstract: Boronated tetrahedral amorphous carbon (ta-C:B) films were prepared by filtered cathodic vacuum arc technique using boron mixed graphite targets. The effect of boron content on the chemical bonding and vibrational properties of these films has been investigated by X-ray photoelectron spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy. It has been found that boron atoms are predominantly configured in a graphitic network, while the carbon atoms in the ta-C:B films are mainly in sp3 hybridization which tend to decrease as boron content increases. The Raman and infrared spectra of ta-C:B films both show prominent features in the regions of 1100–1900 cm−1 and 900–1600 cm−1 respectively. It was identified that the Raman parameters are strongly correlated with the boron content which is due to the clustering of sp2 domains induced by B introduction. The activation of infrared spectrum of ta-C:B film is a consequence of heteroatomic (C–B) vibration combined with changes in the sp2 carbon configuration. And the enhanced infrared absorption of ta-C:B with increased boron incorporation results from the increased effective charges in the delocalized sp2 carbon phase. [Copyright &y& Elsevier]

Abstract: Successful modification of stress and conductivity for tetrahedral amorphous carbon (ta-C) films is realized by phosphorus incorporation via filtered cathodic vacuum arc technique with PH3 as the impurity source. By establishing the structure as a function of phosphorus content, it is found that phosphorus fraction in phosphorus incorporated ta-C (ta-C:P) films increases with varying levels of PH3 from 3 to 30 sccm, and that all samples retain their amorphous structures without remarkable changes, just exhibiting the clustering of sp2 sites and the evolution of structural ordering. Furthermore, the addition of phosphorus causes the compressive stress relaxation in terms of the rearrangement in atomic bonding structures. The increased number of localized electronic π and π⁎ states as hopping sites after phosphorus incorporation results in several orders of magnitude increase in the conductivity, and the films represent the hopping conduction in band tail states in the temperature range of 293–463 K. However, more H induced by excessive PH3 may saturate some defects and compensate the hopping sites, leading to a slight drop in the conductivity. The nature of ta-C:P films as n-type semiconductors is proved from the features of rectifying current–voltage cures. [Copyright &y& Elsevier]