Shirley Chiang est invitée par Patrick Soukiassian,
Abstract :
The growth of silver deposited on Ge(110) was studied with low energy electron microscopy (LEEM) and scanning tunneling microscopy (STM). LEEM movies showed the formation of long, one-dimensional islands as Ag was deposited above 700K, with island nucleation proceeding from defects in the Ge substrate. During deposition, the length of the islands increased while the width remained constant, with island size and distribution dependent on substrate temperature. At 750K, islands were 100 nm wide and 1-20 microns long at 9 ML of coverage. STM images showed that the islands were composed of Ag and that the surface regions between the islands exhibited a reconstruction which is characteristic of pure Ge.
STM was used to characterize the growth of iridium onto the Ge(111) c(2×8) surface at different coverages less than 1ML, with samples annealed to temperatures between 550K and 750K. A new form of growth was observed, consisting of pathways connecting larger iridium islands. As the annealing temperature increased, the iridium growth first formed unusual shapes with finger-like protrusions. Next, these shapes broke apart into smaller islands, which ultimately formed into larger islands at higher temperatures. High resolution images were obtained, allowing insight into the atomic arrangements. We have also done simulations of the growth process, which give insight into the origins of this unusual growth behavior.
We also used LEEM to study the growth of, and transformations between the (4×4), (√3x√3)R30°, and (3×1) structural phases of Ag deposited on Ge(111) both below and above the Ag desorption temperature of 850K.
STM and LEEM Group – UC Davis