Growth of metal nanowires of tunable width

Abstract

Using scanning tunneling microscopy and low-energy electron diffraction it is demonstrated that the deposition of nickel on the hydrogen-stabilized $(5\ifmmode\times\else\texttimes\fi{}1)\text{-H}$ phase of Ir(100) leads to the formation of nickel nanowires of tunable widths and of lengths up to the order of $0.1\text{ }\ensuremath{\mu}\text{m}$. The tuning parameter is the number $n$ of full monolayers deposited on the substrate: with that layer completed the next layer starts to grow by forming nanowires of $n$-atomic width whereby $n$ is in the range $2\ensuremath{\le}n\ensuremath{\le}5$. The formation of the wires is interpreted as decoration or induction of stair rod dislocations which---as we reported earlier---develop to release the 9.0% pseudomorphic tensile strain of the full nickel layers. They lead to long sunk-in wedges at the surface whose width grows linearly with the number of layers deposited and so, by their decoration, nanowires of corresponding width develop. The wedges, and so the Ni wires, appear above single-atomic and macroscopically long Ir wires of the $\text{Ir}(100)\text{\ensuremath{-}}(5\ifmmode\times\else\texttimes\fi{}1)\text{-H}$ substrate which pin the dislocations. Above $n=6$, however, the films become rough and develop a squarelike patterning. It is speculated that the deposition of other metals with the same order of pseudomorphic strain should develop similar nanowires.