Controlling atomistic processes on Pb films via quantum size effects and lattice rotation
Pb depositions on top of Pb(111)/Si(111) films with heights 4 and 5 layers at 40 K show up to a factor of 60 difference in island density. This large difference in nucleation properties between the two films is caused by differences in the critical island size, which in turn is caused by Quantum Size Effects (QSE). The 4-layer film has a critical island size of 1 while the 5-layer film has a critical island size of 5 or larger. This is a remarkable result because even at RT most metals have critical island sizes of 1. In deposition on top of 4- and 5-layer films at 110 K shows that the critical island size is 1 for both films but faster diffusion on the 5-layer films results in a 2 times difference in island density, this too is attributed to QSE. QSE are not the only way to affect the energy and properties of films, lattice rotations between the deposited overlayer and the underlying substrate also have a strong effect. Pb depositions on top of In sqrt(3), In sqrt(31), and In "1x1" results in a multitude of Pb films with different crystal orientations stabilities and morphologies. These experiments show very robust ways to control atomistic processes and the grown nanoscale structures one of the key goals in Nanotechnology.