Aj. Flewitt et al., Growth mechanism of hydrogenated amorphous silicon studied by in situ scanning tunneling microscopy, J APPL PHYS, 85(12), 1999, pp. 8032-8039
In situ scanning tunneling microscopy has been used to study the evolution
of the surface topography of the growing surface of hydrogenated amorphous
silicon (a-Si:H) in order to understand its growth mechanism. The surface i
s found to possess an island-like structure and the island diameter is foun
d to increase with increasing growth temperature. A Fourier analysis of the
surface roughness has an exponent of i = 1.17. A comparison of the roughne
ss of films of different thickness gives a dynamic scaling exponent of beta
= 0.28, but the films are not particularly self-affine in character. It is
argued that the exponent i is not evidence of a viscous flow regime, but t
hat nonstochastic growth of a random network occurs, caused by a preferenti
al hydrogen abstraction at kink-like and step-like surface sites. A simple
simulation of the topography is used to support this conclusion. (C) 1999 A
merican Institute of Physics. [S0021-8979(99)04612-5].