Beschreibung:
Cross-sectional transmission electron microscopy (TEM) was used to observe Au–Si reaction and Si pyramid formation processes in situ. The Au–Si reaction occurred in three stages in a heating process; Au and Si layers reacted through a rough Au/Si interface, the rough Au/Si interface suddenly became flat, and single-crystal Si suddenly changed into a microcrystalline Au–Si layer. Si pyramids were formed in the Au layer in a cooling process, although Au pyramids were formed in the Si substrate by annealing in air. It is concluded that Au- and Si-pyramid formation depends on the Au and Si concentrations in the reaction area, which vary with the degree of surface oxidation.