The growth and structure of gold and silver deposits formed by evaporation inside an electron microscope

Single crystal films of gold and silver have been prepared by evaporation onto molybdenum disulphide inside an electron microscope, in order to allow direct observation of the mode of growth. These experiments provide detailed information on the remarkable liquid-like behaviour of the coalescence of the initial metal nuclei, and the mode of formation of a continuous film. In addition, re-orientation and re-crystallization phenomena are observed, and these effects are shown to be predominant during the growth of a polycrystal-line deposit on an amorphous substrate. The various possible mechanisms for the liquid-like behaviour are considered, by making use of mathematical expressions initially derived to describe the sintering of spherical particles. A semi-quantitative explanation of the liquid-like behaviour is given in terms of the surface diffusion of the metal atoms over the metal islands, the driving force for the mass transfer being the associated reduction in surface energy.