Time-resolved measurements of the formation of single-domain epitaxial Ni films on MgO(111) substrates using in-situ RHEED analysis

The mechanisms behind the formation of smooth [111] oriented single domain epitaxial Ni films grown on MgO(111) substrates by ultra-high vacuum de mag netron sputtering were studied using time-resolved in-situ reflection high energy electron diffraction (RHEED) measurements. The results show that whe ther a single- or a two-domain [111] oriented film forms is decided already during the deposition of the first two or three monolayers of Ni, and that the Ni appears to nucleate as strained islands during this initial growth. This implies that an interaction between the atoms in the second Ni layer and the second and third atomic layers of the substrate must exist, making the Ni atoms always choose the same stacking sequence at a growth temperatu re of 300 degrees C. Prior to growth, the MgO(111) surface is smooth, non-f aceted and without reconstructions. (C) 1999 Elsevier Science B.V. All righ ts reserved.