A study was made of thermally activated changes in Au films, 1 to 10 monolayers thick, which had been deposited onto Pd(110). The films resisted bulk dissolution up to about 500K, according to Auger electron spectroscopy. It was found that, at Au coverages of less than 1.5 monolayers, only a 1 x 1 overlayer structure was observed (using low-energy electron diffraction) over the entire temperature range from 130 to 800K. At coverages of more than 1 monolayer, and after annealing to temperatures above 300K, a (1 x z) diffraction pattern developed. With increasing coverage, the value of z increased continuously from 2 to 3; reaching z = 3, at 4 monolayers. It was suggested that the diffraction pattern reflected a coverage-dependent mixture of small domains of 1 x 2 and 1 x 3 reconstruction, where 1 x 2 was favored at low coverages and 1 x 3 was favored at high coverages. This was explained in terms of a coverage-dependent morphology, and was described as being of Stranski-Krastanov type, with a critical thickness of 2 monolayers.

P.J.Schmitz, W.Y.Leung, H.C.Kang, P.A.Thiel: Physical Review B, 1991, 43[11], 8834-40