STUDIES USING AFM AND STM OF THE CORRELATED EFFECTS OF THE DEPOSITIONPARAMETERS ON THE TOPOGRAPHY OF GOLD ON MICA

A systematic study of the correlated effects of deposition temperature , film thickness and deposition rate on the morphology of gold films o n mica was carried out using atomic force microscopy and scanning tunn elling microscopy. For the range of thicknesses, rates and temperature s concerned, a variety of surface structures, mainly in the form of ro unded mounds, islands, long channel and short channel plateaux topogra phical features were formed under various combinations of these three parameters. The rounded mounds and islands formed, respectively, on th e mica substrate at room temperature and at 150 degrees C were found t o be essentially independent of the film thickness and deposition rate selected. When deposited at higher temperatures (300 degrees C and 44 0 degrees C, a change from islands to channelled features, via the gro wth and coalescence of the islands, was observed either on increasing the film thickness for a given deposition rate (similar to 1.0 Angstro m s(-1)) or on increasing the deposition rate to a given film thicknes s (400 Angstrom). It is evident from the results presented that, where as the film thickness and the deposition rate at a given temperature d etermine to what extent the film has coalesced, the growth temperature influences the lateral size of the surface features formed. In conseq uence, conducting films were found when the gold coverage was greater than or equal to similar to 0.9. Investigation of the vertical charact eristics of the films was also conducted. The origin of all the phenom ena observed can be attributed to competition between secondary nuclea tion and thermally enhanced diffusion processes occurring on the gold surface during deposition and film formation. (C) 1997 Elsevier Scienc e S.A.