It has been recently demonstrated that ion bombardment affects the medium range order parameters in hydrogenated amorphous carbon (HAC), inducing graphitic clustering and reducing the hydrogen content. In this frame, the aim of the present work is to put in evidence the strong correlations existing between the electronic properties of this type of material and both hydrogen concentration and sp2 to sp3 ratio. The changes in the above ratio have been monitored by analysing the complex dielectric function as obtained by electron Energy Loss Spectroscopy (in reflection mode) in the range 0-100 eV and by optical spectroscopy in the range 0-5 eV and comparing the results with those obtained on Ar-implanted HOPG samples. As a consequence of the damage induced by the ion-implantation, the dielectric function shows a strong rearrangement of the sigma --> sigma* transitions together with a change in the relative oscillator strengths on going from pure amorphous carbon to the most hydrogenated (40%) one.
ELECTRONIC-PROPERTIES OF ION-IMPLANTED HYDROGENATED AMORPHOUS-CARBON
COMPAGNINI, Giuseppe Romano
1995-01-01
Abstract
It has been recently demonstrated that ion bombardment affects the medium range order parameters in hydrogenated amorphous carbon (HAC), inducing graphitic clustering and reducing the hydrogen content. In this frame, the aim of the present work is to put in evidence the strong correlations existing between the electronic properties of this type of material and both hydrogen concentration and sp2 to sp3 ratio. The changes in the above ratio have been monitored by analysing the complex dielectric function as obtained by electron Energy Loss Spectroscopy (in reflection mode) in the range 0-100 eV and by optical spectroscopy in the range 0-5 eV and comparing the results with those obtained on Ar-implanted HOPG samples. As a consequence of the damage induced by the ion-implantation, the dielectric function shows a strong rearrangement of the sigma --> sigma* transitions together with a change in the relative oscillator strengths on going from pure amorphous carbon to the most hydrogenated (40%) one.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
