Formation of alkaline-earth template layers on Ge(100) for oxide heteroepitaxy: Self-organization of ordered islands and trenches

作     者：B. R. Lukanov J. W. Reiner F. J. Walker C. H. Ahn E. I. Altman 

作者机构：Center for Research on Interface Structures and Phenomena Yale University New Haven Connecticut 06520 USA Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06520 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA Department of Chemical and Environmental Engineering Yale University New Haven Connecticut 06520 USA 

出 版 物：《Physical Review B》 (Phys. Rev. B Condens. Matter Mater. Phys.)

年 卷 期：2011年第84卷第7期

页      面：075330-075330页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

基　　金：National Science Foundation  NSF 

主　　题：OXIDES ATOMIC structure ATOMIC theory ELECTRON diffraction QUANTUM theory 

摘      要：The first step required for oxide heteroepitaxy with atomically abrupt interfaces on Si and Ge(100) is the formation of an alkaline-earth template layer. The atomic structure of this template layer on Ge(100) was characterized using scanning tunneling microscopy and electron diffraction. At elevated temperatures, Sr immediately roughens the surface; a transition that can be associated with Sr displacing Ge from the surface. With increasing Sr coverage a series of ordered (3 × 4), (3 × 2), (9 × 1), and (6 × 1) phases were observed. Transitions between these phases were accompanied by morphological changes: formation of the (3 × 4) phase smoothed surface; transition to a local (3 × 2) ordering was accompanied by trench formation; ordering of the trenches led to the (9 × 1) structure; and finally, the (6 × 1) structure was characterized by atomic rows. For both Sr and Ba, highly ordered arrays of one-dimensional islands could be produced with double-height steps preventing orthogonal domain formation. We associate the morphological transitions with strain relief of the surface phases and interactions of step ledges.