MORPHOLOGY OF GOLD-FILMS THINNED BY ARGON ION SPUTTER ETCHING

Evaporated gold films and gold films etched by argon ion bombardment to the same thickness are known to exhibit different optical and electrical properties. Transmission electron microscope observations presented in this paper confirm that these differences are caused by different growth/etch film morphologies. The density of islands in a globular film remains nearly constant during etching, in contrast to a steady decrease during deposition. Similarly, the particle density in a nested island film initially remains constant during etching but then increases slightly as some of the islands break up. Films that are initially fully coalesced remain continuous during etching until, when they are very thin, an array of holes of irregular shape and increasing size appears and finally they break up into islands of irregular shape.