화학공학소재연구정보센터
Applied Surface Science, Vol.162, 332-339, 2000
Self assembling growth of triangular pyramidal ge islands on a Si(111)-root 3 x root 3-R30 degrees-B surface phase
Due to the crystallographic identity of Si and Ge, a very interesting system for the preparation of quantum dot arrays is a Ge deposition on top of a cleaned Si surface. The critical thickness for relaxation of the Ge layer on Si amounts to < 2 nm caused by the lattice mismatch. Therefore, Ge quantum dots on Si are very small, strained, and generally statistically distributed over the Si substrate. We will show that the Si(111)- root 3 X-root 30 degrees-B surface phase (BSP), a two-dimensional superlattice of B atoms on top a of Si(lll) substrate deposited between Si and Ge, has the potential to overcome this problem by completely passivating the Si dangling bonds and, therefore, acting as a lubricant between the Si substrate and the epitaxially grown Ge atoms. In general, we will discuss a step-by-step growth model for Ge epitaxy on BSPs, depending on B concentration, degree of misalignment of the Si surface, and growth temperature using atomic force microscopy (AFM) and scanning tunneling microscopy (STM) studies of samples prepared by molecular beam epitaxy (MBE).