Correlation between surface morphology and optical properties for different types of hydrogenated amorphous carbon films grown by plasma enhanced chemical vapour deposition

Various types of hydrogenated amorphous carbon films obtained either from s tandard radiofrequency (RF) plasma enhanced vapour deposition or by an elec tron cyclotron resonance assisted growth method (ECR-RF) were investigated by atomic force microscopy (AFM) and optical transmission. The correlation between optical properties and the surface morphology is evidenced. All fil ms deposited at low RF power present a high optical gap E-04 and exhibit a higher roughness and a lower refractive index n than the small-gap films de posited at high RF power. Under identical RF power, however, ECR-RF large-g ap films show a weaker roughness and a higher value of n than its standard RF counterparts, indicating that the first films are more compact. (C) 1998 Elsevier Science Ltd. All rights reserved.