Preparation of gold thin films by epitaxial growth on mica and the effect of flame annealing

Abstract

Highly crystalline thin films of gold were grown on scratch-free mica. Epitaxial growth was accomplished by heating a fleshly cleaved 8 mm×8 mm piece of mica to 380 °C for 12 h at 1.9×10−7 Torr, followed by gold deposition at 1 Å/s and 380 °C until 100 nm was deposited. After flame annealing, these gold films are observed to have grains that are on average 6300 Å in width with a peak to peak topography of a few atomic layers. Adhesion of gold to mica was accomplished by controlling the temperature and length of bakeout in addition to the temperature of deposition. Films prepared in this manner exhibited excellent adhesion when immersed in all solvents except water. The nearly universally [111] terminated gold films were characterized by scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). STM imaging showed that the gold surfaces exhibit the 22×√3 reconstruction. Flame annealing of films removes contaminants and increases the flat surface area by a factor of 25 relative to the unannealed films as was indicated by both STM and TEM.