GROWTH-MECHANISM OF NI ON PT(110) AT LOW-TEMPERATURE

Ni atoms deposited on Pt(110)-(1 x 1) and(1 x 2) surfaces are studied and compared at 130 K. The Auger uptake curve of Ni on the Pt(110)-(1 x 1) surface shows an exponential-type growth. The intensities of all (1 x 1) LEED spots decrease gradually and exhibit no oscillation durin g the deposition. These results demonstrate that this growth follows t he Volmer-Weber mode. On the other hand, the Auger uptake curve of Ni on the Pt(110)-(1 x 2) surface shows a premonolayer break with an init ial linear growth, The LEED pattern changes from (1 x 2) to a pseudo-( 1 x 1) after Ni atoms fill the sites of the missing rows. After that, the Auger uptake curve turns to an exponential-type and the LEED spot patterns all diminish gradually when more Ni atoms are deposited on th e Pt(110)-(1 x 2) surface. These results demonstrate that the growth o f Ni on the Pt(110)-(1 x 2) surface follows the Stranski-Krastanov (SK ) mode. The growth mechanism is discussed by considering the lattice m ismatch, diffusion, and the surface free energies of the adsorbate and the substrate.