STM STUDY OF GE OVERLAYERS ON SI(001)

The structures of microscopically small Ge islands on the Si(001) surface were observed by an ultrahigh vacuum scanning tunneling microscope. After the Ge deposition of 0.1-0.2 monolayer (ML) on the Si substrate at 300-degrees-C, Ge islands composed of 1-5 dimer rows were observed. The observed structures indicated that the ordered arrangement of the buckled dimer rows varies with the number of dimer rows and that the position of a buckled Ge dimer has an interesting correlation with the position of a substrate Si dimer. A Ge dimer row separated by a missing dimer alternately was also observed. The stability of the Ge dimer row is discussed.