The effect of underlayer-modified atomic monolayer on the mechanism of subsequent film growth

We have studied the influence of the upper Si monolayer (ML) in Fe-Si interlayers on the mechanism of subsequent growth of 7-ML-thick Cu films during molecular beam deposition. The Fe–Si interlayers and Cu films were studied in ultrahigh vacuum by the methods of electron energy loss spectroscopy (EELS) and Auger electron spectroscopy (AES). The final morphology of samples was examined in air by the atomic force microscopy. It is established that the growth of a Cu film on a Si(1 ML)/Fe$_2$Si$_3$(5 ML)/Si(001) structure has a pseudolayer character (with dissolution of the uppermost Si monolayer), while the growth of Cu on a Si(1 ML)/Fe(1 ML)/Si (1 ML)/Fe(1 ML)/Si(001) structure proceeds in the form of islands. This behavior is explained by different chemical states of the uppermost Si monolayer, which is modified by Fe–Si underlayers with different structures.