LEEM and STM observations of Growth of Nanowires of Ag on Ge(110) and Surface Structural Phases of Ir on Ge(111)*

We have used both low energy electron microscopy (LEEM) and scanning tunneling microscopy (STM) to characterize the growth of silver on Ge(110) and iridium on Ge(111) as a function of coverage, deposition temperature, and annealing temperature. We observed 1D island growth along [-110] as Ag is deposited onto Ge(110) above 430 C. Island dimensions varied with deposition temperature. At 480 C, Ag islands are $\sim $100nm wide and 1-20 $\mu $m long for 9 ML coverage. Between 380 C and 430 C, we observed two novel low coverage phases, with the higher coverage phase completing at 0.12 ML. Ir deposited onto the Ge(111) c(2x8) above 400 C forms a ($\surd $3x$\surd $3)R30$^{o}$ phase, with island size dependent upon substrate temperature during deposition. Deposition at 400-425 C produces Ir islands, which are 1-20 nm in diameter at 0.5 ML coverage. Island heights range from one to several atomic layers, and exhibit a unique growth mode with islands connected by ``streamers'' of Ir. We observed Stranski-Krastanov growth in LEEM at 670 C. Ir desorbs from Ge(111) at 870 C, beginning from areas of high step density.