Structure and morphology of the PdrMgO 001/ interface during its formation

The growth of Pd on MgO 001.has been investigated by grazing incidence X-ray scattering. Deposits in the range 0.2 to 183 monolayers ML.were analyzed in situ, in UHV. The growth proceeds by nucleation and islands growth from 0.2 ML. The coalescence starts at 18 ML and is complete at 35 ML. Pd is in cube on cube epitaxy with respect to the MgO 001. substrate, and has a lattice parameter close to that of bulk Pd. The islands are coherent with the substrate up to ;5 ML of Pd deposited. Above 5 ML, interfacial misfit dislocations are introduced at the edges of the islands. Above 35 ML, the interfacial misfit edge dislocations reorder to form a square network. The dislocation lines are oriented along 110: directions, and the Burger’s vectors are of the 1r2 110:type. q1999 Elsevier Science B.V. All rights reserved