Structural Studies of Strained and Nanostructured Rare Earth Silicides and Germanides Using MEIS and STM.

作为微处理器核心的数字开关的硅晶体管变得越来越小，以提高开关速度，半导体行业面临着许多技术和基础方面的挑战。随着器件尺寸的缩小，电子器件的一个越来越重要的领域是金属和半导体材料之间的结或界面。不仅需要了解这种金属-半导体界面的性质，而且需要开发新的和新颖的界面，这将有助于这种理解，并在未来的挑战中具有潜在的益处。新的界面包括磁性材料和半导体之间的界面，它提供了一条控制电子自旋的途径。这是一个非常活跃的研究领域，有可能开发出各种新器件，包括传感器。这里的研究是在支撑这些技术发展的基本端，它是确定一系列金属-半导体界面的结构，并通过利用不同稀土硅化物（硅和镧系金属的化合物）之间的间距的细微差异来研究修改结构的方法，以在硅化物上的材料生长中产生不同量的应变。其他方法将是使用缓冲层、不同的生长温度（包括冷却到室温以下）和不同的半导体衬底，目的是防止某些硅化物形成或修改界面结构。这些结构的研究将进行使用中能离子散射（MEIS）在英国国家MEIS设施在达雷斯伯里和扫描隧道显微镜（STM）在约克的技术。MEIS使用一束离子（通常是氢离子）散射材料中的原子，它们的散射能量取决于离子撞击的原子的质量，而在特定方向离开材料的数量取决于它们的输出路径是否被材料中的原子阻挡。该技术具有两个关键优势：它可以在材料中实现亚纳米深度分辨率，并且对材料中的原子种类敏感。因此，它非常适合于研究半导体上的金属，其中金属和半导体原子之间存在良好的质量差，并且金属原子被并入界面中，例如在硅化物形成的情况下。

As the silicon transistor, which is the digital switch at the heart of the microprocessor, gets smaller and smaller in order to increase switching speeds there are many challenges facing the semiconductor industry which are both technological and fundamental. One area of electronic devices which is increasingly important as devices shrink in size is the junction or interface between metals and semiconductor material. There is a need not only to understand the properties of this metal-semiconductor interface, but to develop new and novel interfaces which will aid this understanding and be of potential benefit in the challenges ahead. New interfaces include those between magnetic materials and semiconductors, which offer a route to controlling the spin of the electron. This is a very active area of research which has the potential for a wide range of new devices, including sensors. The research here is at the fundamental end which underpins these technological developments, it is to determine the structure of a range of metal-semiconductor interfaces and to investigate ways of modifying the structure by exploiting the subtle differences in the spacings between different rare earth silicides (compounds of silicon and lanthanide metals) to generate differing amounts of strain in the growth of materials on the silicide. Other approaches will be to use buffer layers, different growth temperatures (including cooling below room temperature), and different semiconductor substrates with the aim of preventing certain silicide formations or modifying the interface structure. These structural studies will be carried out using the techniques of medium-energy ion scattering (MEIS) at the UK national MEIS facility at Daresbury and Scanning Tunnelling Microscopy (STM) at York. MEIS uses a beam of ions (usually hydrogen ions) which scatter off the atoms within the material, their scattered energy depends on the mass of the atom that the ions have hit and the number leaving the material in specific directions depends on whether their outgoing path is blocked by atoms in the material. This technique has two key advantages: it can achieve sub-nanometre depth resolution in materials and is sensitive to the atomic species in the material. It is therefore well suited to the study of metals on semiconductors where there is good mass difference between the metal and semiconductor atoms, and where the metal atoms are incorporated into the interface such as in the case of silicide formation.