Dynamic roughening of tetrahedral amorphous carbon.
The roughness of tetrahedral amorphous carbon (ta-C) films grown at room temperature is measured as a function of film thickness by atomic force microscopy, to extract roughness and growth exponents of alpha approximately 0.39 and beta approximately 0-0.1, respectively. This extremely small growth exponent shows that some form of surface diffusion and relaxation operates at a homologous temperature of 0.07, much lower than in any other material. This is accounted for by a Monte Carlo simulation, which assumes a smoothening during a thermal spike, following energetic ion deposition. The low roughness allows ta-C to be used as an ultrathin protective coating on magnetic disk storage systems with approximately 1 Tbit/in.(2) storage density.
Casiraghi
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C
Engineering Department, Cambridge University, Cambridge CB2 1PZ, United Kingdom. cc324@eng.cam.ac.uk
Ferrari
A C
AC
Ohr
R
R
Flewitt
A J
AJ
Chu
D P
DP
Robertson
J
J