Apparatus for studying the structure and evolution of atomically-ordered domain boundaries, kinks and vertexes

在许多种类的电子材料中，例如多晶Si或高k晶体管，诸如太阳能电池效率或击穿场的性质取决于晶粒的尺寸和空间排列以及界面（微结构）的分布。材料经常被退火以通过再结晶和晶粒生长来引发微观结构转变。虽然，有大量的文献晶粒生长和晶粒粗化，而不是详细的结晶信息界面和界面能，理论模型通常假设界面能是各向同性的。为了超越这一点，有必要根据其微观结构对界面进行分类，这可能导致对加工，结构和材料性能之间关系的定量理解。因此，我们感到兴奋的事实是，我们已经发现了一个二维模拟的三维电子材料，具有高度各向异性分布的界面（域边界），这是服从详细的调查，在原子水平。具体来说，我们已经开发出一种在原子级平坦的Si表面上生长Ge膜的方法，使得其包含由原子级有序边界分离的结晶域。使用这个模型系统，它是可能的研究：域的分布，边界的分布，边界的原子结构和边界，扭结和顶点的时间演化。为了充分利用这个系统，我们需要电子设备，使我们能够同时进行隧道和力显微镜。这将使我们能够准确地确定原子在边界区域的位置，并在许多情况下区分Si和Ge原子。这些研究将提供原子级的信息，决定各向异性分布的边界和增长的区域在良好的表征模型系统的物理因素。该设备还将为每年6名高素质人员提供新的培训机会。

In many classes of electronic materials, such as polycrystalline Si or high-k dielectrics, properties such as solar cell efficiency or breakdown field depend on the size and spatial arrangement of crystalline grains and the distribution of interfaces (microstructure). Materials are frequently annealed to initiate micro-structural transformation via re-crystallization and grain growth. Although, there is a large literature on grain grown and grain coarsening, in lieu of detailed crystallographic information about interfaces and interface energies, theoretical models normally assume that interface energies are isotropic. To go beyond this, it is necessary to classify interfaces according to their microstructure and this could lead to a quantitative understanding of the relationship between processing, structure and material properties. Consequently, we are excited by the fact that we have discovered a two-dimensional analog of a three-dimensional electronic material that has a highly anisotropic distribution of interfaces (domain boundaries) that is amenable to detailed investigation at the atomic level. Specifically, we have developed a way of growing a Ge film on an atomically flat Si surface so that it contains crystalline domains separated by atomically ordered boundaries. Using this model system it is possible to study: the distribution of domains, the distribution of boundaries, the atomic structure of boundaries and the temporal evolution of boundaries, kinks and vertexes. To take full advantage of this system we require electronics that will allow us to perform tunneling and force microscopy simultaneously. This will allow us accurately determine the position of atoms in the boundary region and also discriminate between Si and Ge atoms in many cases. These studies will provide atomic-level information about the physical factors that determine the anisotropic distribution of boundaries and the growth of domains in well-characterized model system. This apparatus will also provide novel training opportunities for six highly qualified personnel/year.