Self-assembly of ultrafine nanolines upon Ho reaction with the Ge(001) surface

The reaction of the rare earth metal Ho with the Ge(001) surface at 440 °C has been studied by scanning tunneling microscopy (STM). The self-assembly of ultrafine nanolines growing along substrate 110 directions has been observed, and based on atomic resolution STM images, the authors propose a model of the nanolines and comment on their relationship to the very initial stages of growth of a hexagonal germanide structure. The authors further report the presence of nanoscale trenches associated with well-ordered lines of missing dimer defects and discuss the relationship of these to the nanolines. Their results have possible applications involving interconnects or templating in nanoscale devices, and additionally, may provide insight into the nucleation mechanism of coarser nanowires.