Atomic and Electronic Structure Investigations of Adlayers on Semiconductors with Photoemission Holographic Imaging and Spectroscopy

9505618 Lapeyre该项目将使用同步辐射光电子能谱和其他电子能谱仪来研究半导体表面覆盖层的结构和电子性质。重点是光电子衍射实验的性能，其中扫描的能谱可以被反转，以获得光电发射原子及其近邻的三维图像。这种反转是一种基于全息原理的类傅里叶变换，不需要任何外部输入即可获得图像。这项技术已经在包括Al、Ga、As和Se在内的各种硅表面上得到了验证。未来研究特别感兴趣的是影响半导体表面生长性质的结构变化--包括同质和异质外延--以及表面的电子性质。光电子全息术将被应用于各种吸附在硅、镓和锌上的体系的结构测定。全息技术的两个新应用将被开发：a)在化合物半导体衬底上的单一吸附，以及b)在元素半导体衬底上的多个吸附。正在开发一种新的原子级材料表征技术--光电全息术，并将其应用于与电子学和光电子学有很强技术相关性的材料的基础合成和工艺研究。该项目的一个重要特点是在材料研究的基础和技术领域对学生进行培训。***

9505618 Lapeyre This project will use synchrotron radiation photoemission spectroscopy and other electron spectroscopies to study the structure and electronic properties of overlayers on semiconductor surfaces. Emphasis will be given to the performance of photoelectron diffraction experiments where scanned energy spectra can be inverted to obtain three dimensional images of the photoemitting atom and its near neighbors. The inversion is a Fourier-like transform based on the holographic principle and does not require any external input to obtain an image. The technique has been demonstrated on various systems including Al, Ga, As and Se on Si surfaces. Of particular interest for future investigations are structural changes that influence the nature of growth--both homo- and hetero-epitaxy--at semiconductor surfaces and the electronic properties of surfaces. Photoemission holography will be applied to structure determination of systems composed of various adsorbates on Si, GaAs, and ZnSe. Two new applications of the holographic technique will be developed: a) a single adsorbate on a compound semiconductor substrate, and b)multiple adsorbates on an elemental semiconductor substrate. %%% A new atomic-level materials characterization technique, photoemisson holography, is being developed and applied to basic synthesis and processing research studies of materials with strong technological relevance to electronics and optoelectronics. An important feature of the program is the training of students in a fundamentally and technologically significant area of materials research. ***