Structural Studies of Alkali Metals on Silicon and Germanium

硅和锗上碱金属的结构研究

• 批准号: 9301309
• 负责人: Piero Pianetta
• 金额: $ 30万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1997-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9301309&HistoricalAwards=false
• 关键词: Structural; Studies; Alkali; Metals; Silicon

9301309 Pianetta This proposal describes experiments designed to quantitatively determine the atomic structure of alkali metals on surfaces of silicon and germanium. Experimentally, emphasis will be placed on the soft x-ray standing wave (XSW) technique performed in conjunction with surface extended x-ray adsorption fine structure (SEXAFS). This will be followed with scanning tunneling microscopy (STM) to aid in the final structural determination. XSW provides the perpendicular distances between the substrate planes and the overlayer, while SEXAFS allows precise bond length determinations. Together these techniques can determine adsorption angles and hence interfacial geometries of complex metal-semiconductor systems. In combination with STM, these techniques form a very complimentary set of probes for the complete structural determination at an interface. The main goals of this proposal are to achieve an in- depth understanding of the interfacial atomic structure alkali metal overlayers and to correlate the information with their electronic properties. In addition, this structural and electronic information will test and further develop state-of-the-art theoretical calculations. %%% Novel electronic properties of interfaces have enormous commercial applications in electronics. The simplest such interface, used as a building block of most practical devices, is a junction between a metal and a semiconductor. In this proposal, the microscopic (atomic) structure of single layers of alkali metals (such as sodium, potassium) deposited on silicon and germanium will be studied. These layers display a unique ability to substantially lower the potential barrier for election escape from the semiconductor and, because of that, are used in infrared detectors and photocathodes. This investigation will use several techniques based on synchrotron radiation. In particular, a newly developed standing wave method which allows precise location of foreign atoms on surfa ces will be utilized. The results will be of fundamental interest and have potential to aid development of new materials for technological applications. ***

9301309 Pianetta该提案描述了旨在定量测定硅和锗表面上碱金属原子结构的实验。 实验上，重点将放在软X射线驻波（XSW）技术与表面扩展X射线吸附精细结构（SEXAFS）结合进行。 这将随后与扫描隧道显微镜（STM），以帮助在最终的结构测定。 XSW提供了衬底平面和覆盖层之间的垂直距离，而SEXAFS允许精确的键长测定。 这些技术可以一起确定吸附角，从而确定复杂的金属-半导体系统的界面几何形状。 结合STM，这些技术形成了一套非常互补的探针，用于在界面处进行完整的结构测定。 本建议的主要目标是实现对碱金属覆盖层的界面原子结构的深入理解，并将这些信息与它们的电子性质相关联。 此外，这些结构和电子信息将测试和进一步发展最先进的理论计算。 界面的新颖电子特性在电子学中具有巨大的商业应用。 最简单的界面是金属和半导体之间的结，它被用作大多数实用器件的构建块。 在这项提议中，将研究沉积在硅和锗上的碱金属（如钠、钾）单层的微观（原子）结构。 这些层显示出显著降低电子从半导体逃逸的势垒的独特能力，因此，用于红外探测器和光电阴极。 这项研究将使用几种基于同步辐射的技术。 特别是，一个新开发的驻波方法，允许精确定位的表面上的外来原子将被利用。 研究结果将具有根本意义，并有可能帮助开发用于技术应用的新材料。 ***