SGER: Surface and Sub-Surface Imaging at Nanometer Scales Using Picosecond Thermoacoustic Microscopy

摘要提案编号：CTS-9910823主要研究者：A.在纳米尺度上操纵物质、观察和控制物理和生物现象的能力为研究人员提供了丰富的基础科学和新技术的机会。 这项研究最重要的方面之一是能够以纳米尺度的空间分辨率观察物体和现象。 扫描隧道显微镜（STM）和原子力显微镜（AFM），以及一般的扫描探针显微镜（SPM），使得在固体表面上成像单个原子和观察单个生物分子成为可能。 然而，目前的SPM未能满足纳米技术的一些基本需求，即：（i）能够以纳米垂直和横向分辨率对表面以下的物体进行三维成像;（ii）能够进行光谱分析，以确定材料的化学成分。 由于以下原因，三维成像极其重要：（a）微电子芯片正变得越来越多层;（B）生物分子具有三维结构和功能;（c）纳米相材料通常是三维的。 弹道电子发射显微镜（BEEM）[1]能够在表面以下约100-200 A的距离成像并进行电子光谱学。 然而，它需要金属和半导体材料来操作。 使用AFM的磁共振成像[2，3]可以提供三维图像，尽管需要在非常低的温度（1 K）下进行实验以获得亚微米分辨率。要对物体进行三维成像，有两种可能的方法：（i）发射某种形式的辐射，并在空间中的某个点测量其时间分辨散射（弹性或非弹性）。超声成像）;或（ii）通过外部场将共振激发限制在特定位置（例如，核磁共振）。 本项目将采用第一种方法。 它将结合联合收割机两种技术--用于高横向分辨率的扫描探针显微镜和用于高垂直分辨率的皮秒热声--以获得纳米级分辨率的三维图像。

ABSTRACTProposal Number: CTS-9910823Principal Investigators: A. MajumdarThe ability to manipulate matter and to observe and control physical and biological phenomena at nanometer scales is providing researchers with rich opportunity for basic science as well as new technology. One of the most important aspects of this research is the ability to observe objects and phenomena with nanometer scale spatial resolution. The scanning tunneling (STM) and the atomic force microscopes (AFM) and, in general, the whole class of scanning probe microscopes (SPMs), have made it possible to image single atoms and observe single biological molecules on a solid surface. The current SPMs, however, fail to address some fundamental needs in nanotechnology, namely: (i) the ability to image objects below the surface, i.e. in three dimensions, with nanometer vertical and lateral resolution; (ii) the ability to perform spectroscopy in order to identify the chemical content of the material. Imaging in three dimensions is extremely important because of the following reasons: (a) microelectronics chips are becoming increasingly multilayered; (b) biological molecules have three-dimensional structure and function; (c) nanophase materials are generally three dimensional. The ballistic electron emission microscope (BEEM) [1] is able to image and perform electron spectroscopy below the surface to a distance of about 100-200 A. However, it needs a metal and a semiconducting material to operate. Magnetic resonance imaging using the AFM [2,3] can provide a three-dimensional picture, although one needs to perform experiments at very low temperatures ( 1 K) to obtain sub-micron resolution. To image objects in three dimensions, there are two possible approaches: (i) to either emit some form of radiation and measure its time-resolved scattering (elastic or inelastic) at a certain point in space (eg. ultrasonic imaging); or (ii) to confine resonance excitation to a certain location by an external field (eg. nuclear magnetic resonance). This project will use the first approach. It will combine two techniques - scanning probe microscopy for high lateral resolution and picosecond thermoacoustics for high vertical resolution - to obtain three-dimensional images with nanometer-scale resolution.