Investigation of the Mechanism of Ge/Si heteroepitaxial Growth with Interfacial Reactions

近年来，Ge/Si超晶格在光学器件中的应用受到了广泛的关注，因为Ge/Si多层结构具有直接带隙。为了制备这些Ge/Si异质结构，必须对异质外延生长和生长界面处的固相反应机理有透彻的了解。本文用反射高能电子衍射（RHEED）原位观察研究了GeH_4气体源分子束外延Ge在（100）Si和（811）Si衬底表面生长初期的生长过程。在这项工作中的重点已被放置在异质外延生长与生长界面处的界面反应的机制。薄膜生长的动力学行为是：首先以单层过生长方式形成应变薄膜，薄膜具有平行取向的外延关系，薄膜中的Ge岛与Ge岛之间的相互作用是相互作用的，薄膜中的Ge岛与Ge岛之间的相互作用是相互作用的。 关于我们 在300-700 ℃的检查衬底温度下进行生长。在（100）Si表面上的岛生长阶段，生长的岛的主要面最初是（811）Ge面，并且随着生长而最终变为1311）Ge面。在（811）Si表面上生长岛时，生长出具有（811）面的板状Ge岛，但随着进一步生长，主要面变为1311）Ge和（100）Ge面。这些生长过程与（100）Si表面Ge薄膜的生长过程雅阁。结果表明，在（811）Si表面和（100）Si表面上，具有（8111）晶面的Ge岛在岛生长的初始阶段是能量稳定的，Ge和Si原子在岛生长的初始阶段形成了有序结构，这是生长界面附近固相反应的结果。今后，我们将进一步研究{811}面的热稳定性，并通过界面反应阐明Ge/Si异质结系统的异质外延生长机制和有序结构的起源。少

Recently, the application of Ge/Si superlattices to optical devices has received considerable attention, because the Ge/Si multilayer structure has a direct band-gap. In order to fabricate these Ge/Si heterostructures, it is essential to have a thorough understanding of the mechanism of the heteroepitaxial growth and solid phase reactions at growing interfaces. In the present work, the growth process in the initial stage of growth of Ge on (100)Si and (811)Si substrate surfaces by gas source molecular bean epitaxy using GeH4 has been studied by in-situ reflection high energy electron diffraction (RHEED) observation. Focus in this work has been placed on the mechanism of the heteroepitaxial growth with the interfacial reactions at the growing interfaces. The following growth process and dynamic behavior of the film growth have been made clear.A strained film by the monolayer overgrowth mode is formed initially with an epitaxial relationship of the parallel orientation, and Ge islands wi … More th facets are grown with proceeding the growth over examined substrate temperatures of 300-700ﾟC. In the island growth stage on (100)Si surfaces, the predominant facet of the growing islands is (811)Ge planes initially and this changes to 1311)Ge eventually with growth. In the case of the island growth on (811)Si surfaces, plate-shaped Ge islands with (811) facets are grown, but the predomi nant facet changes to 1311)Ge and (100)GE planes with the further growth. These growth processes accord with those of Ge films on (100)Si surfaces. It is concluded that Ge islands with (8111 facets are energetically stable in the initial stage of the island growth on the (811)Si surfaces as well as the (100)Si surfaces.It has been found that an ordered structure of Ge and Si atoms are formed in the initial steps of growth, which results from the solid phase reaction near the growing interfaces. In future, we intend to investigate the thermal stability of the {811} surface and make clear the mechanism of heteroepitaxial growth and the origin of the ordered structure in the system of the Ge/Si heterostructure with the interfacial reaction. Less