Vacancy-Vacancy Interaction on Ge-Covered Si(001)

Abstract

When Ge atoms are deposited onto a Si(001) substrate, dimer vacancies are created in the strained system. At sufficiently high concentrations, interactions between the vacancies cause them to line up, resulting in the ($2\times n$) reconstruction. By analyzing the thermal fluctuations around the ideal ($2\times n$) structure with scanning tunneling microscopy and using transfer matrix theory, the form of the dimer vacancy-vacancy interaction and a value for its magnitude have been determined.