Formation of Ge-Pt layer compound on Pt(100)

We found a novel Ge-Pt layer compound on the Ge/Pt(100) surface by using alkali ion scattering spectroscopy (ALISS), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM). This surface alloy is produced after Ge deposition and annealing at 600 K, and explains the surprising apparent stability of a Ge adlayer on Pt(100) to very high temperature. At low Ge deposition amounts, Ge atoms form a c(2×2) overlayer, but for deposition larger than 0.5 ML, excess Ge dissolves into the third layer in the c(2×2) positions to form the ordered layer compound with excess Ge diffusing more deeply into the substrate.