Spinodal decomposition driven formation of Pt-nanowires on Ge(001)

Abstract

Using low energy electron microscopy, we have found that the deposition of Pt on Ge(001) leads to the formation of a surface confined eutectic liquid when the system is heated above 980 K. From the bulk phase diagram we derive the composition of the eutectic phase: Ge $_{0.78}$ Pt $_{0.22}$ . Upon solidification and further cooling down, two distinct types of terrace emerge, the so-called α and β terraces, which have been assigned previously as relatively Pt-poor and Pt-rich, respectively. Immediately after solidification β terraces fully cover the surface, while further cooling leads to their partial transformation into α terraces. Subsequently, Pt nanowire domains nucleate and grow exclusively on β terraces at about 600 K. The results are discussed using spinodal decomposition concepts and reveal a new pathway for nanowire formation.

Keywords

• nanowires
• germanium
• low energy electron microscopy
• 68.37.Nq
• 68.37.Ef
• 68.47.Fg