PSEUDOMORPHIC GROWTH OF THIN CU FILMS ON PD(110)

The growth of thin Cu films on Pd(110) has been studied by variable te mperature scanning tunneling microscopy in the temperature range 250 l ess than or equal to T-s less than or equal to 900 K. Cu adatom diffus ion on the substrate is highly anisotropic and determines the submonol ayer Cu island shapes. This leads at low deposition temperatures (T-s less than or equal to 300 K) and low Cu coverages(theta (0.1 less than or equal to ML) to the formation of monatomic Cu chains oriented alon g [1 $($) over bar$$ 10]. At higher coverages and/or deposition temper atures two-dimensional (2D) islands of anisotropic shape grow. At 300 K the 2D Cu-islands are arranged in a semi-ordered striped domain stru cture along the [001] direction. In the Cu multilayer range, the film growth mode can be varied through deposition temperature control. Micr orough Cu films consisting of small 3D clusters grow below 400 K. Bi t ween 400 and about 550 K, Stranski-Krastanov growth with a critical th ickness of one monolayer takes place. At 550 K, a transition to a laye r-by-layer step-now mode occurs. Flat Cu multilayers are found to be ( 1 X 1) pseudomorphic up to a critical thickness of 5 ML. Thicker films partially relieve their misfit strain through uniaxial relaxation int o a (29 X 1) high-order commensurate structure. At temperatures above 750 K, we observe CuPd intermixing.