CAREER: Directed Assembly of Nanoparticles; A Tool to Enable the Fabrication of Nanoparticle Based Devices

University Of Minnesota-Twin Cities, Minneapolis MN

Investigators

Abstract

Goals. The first research objective of this CAREER program is to develop a parallel tool to position nanoparticles and small components onto surfaces. The strategy that will be developed is based on directed self-assembly; it uses a patterned surface with areas (receptors) that interact with nanoparticle based device components. The interaction driving the assembly process is based on electrostatic forces. The central goal of the research is to demonstrate that nanotechnological devices can be assembled by the directed self-assembly of nanoparticle building blocks. As a first device example the research will focus on the fabrication of a vertical flow field effect transistor that uses a silicon nanoparticle as channel element. The specific CAREER objectives are: To develop a parallel tool that is based on directed self-assembly to position nanoparticles and small components on surfaces with sub 100 nm resolution. To study the key factors and ultimate resolution in theory and experiment. To apply the developed tool to fabricate nanotechnological devices in general and a vertical flow FET in particular. To foster a cross-disciplinary education and outreach to a broad community. Intellectual merits. Nanoparticles can provide a variety of functions and are considered as building blocks for future nanotechnological devices. Examples of such devices are single electron transistors, quantum-effect-based lasers, photonic bandgap materials, filters, and wave-guides. Device prototypes have been realized using random particle deposition and single particle manipulation. Such strategies are useful to fabricate and explore new device architectures; however, their lag in yield and speed will have to be overcome in the future. Fabrication strategies that are based on self-assembly and directed assembly may overcome these difficulties. This program will advance the knowledge in the area of directed self-assembly. The research will focus on electrostatic interactions because they are long-range and non-material specific (any particle can be trapped). The PI invented a parallel process to pattern charge at 100 nm resolution (published in Science 2001, see bibliography). In a preliminary experiment, these charge patterns allowed to direct the assembly of nanoparticles from the gas phase and liquid phase. These findings demonstrate that electrostatic forces resulting from surface charges or externally biased electrodes can be used to guide nanoparticles to specific locations on a substrate. The investigator believes that such an electrostatically-directed self-assembly, because it is based on long-range electrostatic interactions, will give a significant advantage over other strategies that use protein recognition, DNA hybridization, hydrophobicity/hydrophilicity, and magnetic interaction. The CAREER program lays down the ground work to accomplish the PI's long term research goal, which is to use a variety of different short range and long range interactions to direct the assembly of small components and nanoparticles to fabricate functional devices in two- and three dimensions. Broader impact. It is difficult to overstate the broader impact of the research component of this CAREER pogram, if it proves successful. For example, materials could be created as nanoparticles in the vapor or in solution, where they could be processed using well established methods. The ability to localize particles and small components of arbitrary materials on arbitrary substrates could allow the merging of technologies based on otherwise incompatible materials. Examples of applications include quantum electronic devices (addressed in this program), integrated circuits on plastics or fabrics for wearable intelligence, and merged optical/electronic structures for optical off-chip and cross-chip communication. Educational objectives. The educational objectives of the CAREER program focuses on creating awareness and transmitting excitement about the PI's research as well as exploratory, interdisciplinary research in general. It emphasizes on the importance of providing continuous opportunities for student involvement throughout their academic careers. Strongly influenced by the PI's educational experiences, the educational approach includes the following key points: 1) outreach to high school students and teachers, 2) undergraduate education, 3) undergraduate research, 4) graduate education, 5) graduate research, and 6) outreach to the general public. Societal implications. "Advances in nanoscience and nanotechnology promise to have major implications for health, wealth, and peace in the upcoming decades. Knowledge in this field is growing worldwide, leading to fundamental scientific advances. In turn, this will lead to dramatic changes in the ways that materials, devices, and systems are understood and create." - after Mihail C. Roco. This research is one element to advance knowledge. It suggests a dramatic change in the way that devices and systems are created.