ELECTRICAL AND OPTICAL-PROPERTIES OF AMORPHOUS-CARBON LAYERS - LIMITS OF THE ISOTROPIC LAYER MODEL

The electrical and optical properties of amorphous carbon layers deposited by different techniques are presented and compared. The layers investigated may be divided into two groups: low refractive index transparent and insulating samples and, on the contrary, high refractive index strongly absorbing and conducting films. Experimental results are presented which indicate that the strongly absorbing and conducting samples exhibit anisotropic properties observed by means of cross-sectional transmission electron microscopy, while transparent and insulating samples are electrically and optically isotropic. An attempt has been made to explain the effect of the ambiguity of electrical and optical properties on the basis of a simple mixing model. The model allows us to reproduce the high refractive indices of absorbing and conducting layers as well as the low refractive index transparent and insulating films.