Fabrication and Electrical Characterization of Atomic-Scale Wires

这项研究的最终目标是制造原子级的电线，甚至可能只有一个原子的直径，并对其进行低温电测量。这些金属线将通过自然生长和扫描隧道显微镜（STM）的模式相结合而产生。早期的实验将包括STM以前没有研究过的金属链形成系统的成像和链稳定性的研究。在链和宏观接触之间架起桥梁的中等尺度接触探针将使用阶梯边缘蒸发或STM化学气相沉积。这一阶段的实验将检查这些中等规模的衬垫对原子链的破坏性影响，以及衬垫和原子链之间电接触的任何问题。一旦样品制成，它将被转移到同一个超高真空室的低温阶段，并测量其电学性能。作为上述所有实验的前奏，将进行杂散电容对单电子隧穿（SET）影响的研究。这个基础研究项目将研究在制造原子级电子电路过程中一些明显的挑战。我们的最终目标是制造出所有此类电路中最简单的电路，即原子尺度的导线（甚至可能只有一个原子的直径），并对其进行低温电测量，以探索量子力学效应。我们将利用半导体衬底上金属的自然有序、扫描隧道显微镜的模式和“阶梯边缘蒸发”（一种在衬底上使用小步骤来创建纳米级结构的技术）的组合来制造金属线。有几个明显的挑战。对于大多数材料来说，电线内部导电所需的电子似乎会被制造电线的衬底吸走。电线和宏观世界之间的电连接的产生可能会破坏电线，或者电线可能会被热波动破坏。电线之间的电接触和宏观接触可能是困难的。然而，我们有信心能够应对每一个挑战，并提出了一些有希望的战略。＊＊＊

9623355 Smith The ultimate goals of this research are to fabricate atomic- scale wires, perhaps even one atom in diameter, and to make low- temperature electrical measurements on them. The wires will be created by a combination of natural growth and patterning with the scanning tunneling microscope (STM). Early experiments will include imaging of a metal-chain- forming system not previously studied by STM and studies of chain stability. Intermediate-scale contact probes to bridge between the chains and macroscopic contacts will be made using either step-edge evaporation or STM chemical vapor deposition. Experiments in this phase will examine any disruptive effects of these intermediate-scale pads on the atomic chains, and also any problems with electrical contact between the pads and the chains. Once a sample is made, it will be transferred to a low-temperature stage within the same ultrahigh vacuum chamber, and its electrical properties will be measured. As a prelude to all the above experiments, a study of the effects of stray capacitance on single electron tunneling (SET) will be performed. %%% This basic research project will examine some of the apparent challenges in creating atomic-scale electronic circuits. Our ultimate goals are to make the simplest of all such circuits, an atomic-scale wire (perhaps even one atom in diameter), and to perform low-temperature electrical measurements on it to explore quantum mechanical effects. We will make the wire using a combination of natural ordering of metals on semiconductor substrates, patterning with the scanning tunneling microscope, and "step-edge evaporation", a technique which uses small steps in the substrate to create nanometer-scale structures. There are several apparent challenges . For most materials, it appears that the electrons needed for electrical conduction within the wire would be sucked away by the substrate on which the wires are created. The creation of electrical connections betw een the wires and the macroscopic world may disrupt the wires, or the wires might be disrupted by thermal fluctuations. Electrical contact between the wires and the macroscopic contacts may prove difficult. However, we are confident that each of these challenges can be met, and suggest several promising strategies. ***