Semiconducting nanowires, high aspect ratio rods with diameters of order tens of nanometers, have received much attention in recent years, due to their anticipated (and in some cases observed) novel optical, thermal, electrical, and mechanical behavior. To date, silicon (Si) nanowires have been the most extensively studied owing both to the technological relevance of the material and to the relative simplicity of the synthesis. However, a number of critical applications, such as high-efficiency electrochemical storage devices and high brightness miniature neutron sources, highlight the limitations of Si nanowires and the need for more robust materials systems. Silicon carbide (SiC) nanowires were chosen for these studies because of the exceptional physicochemical stability of this material. This research project aims to gain a fundamental understanding of the growth mechanism of silicon carbide nanowires and the parameters that control their morphological and electrical properties.
TECHNICAL DETAILS: The specific SiC nanowire synthetic approach chosen is Ni-catalyzed chemical vapor deposition from single precursor methyltrichlorosilane and with ammonia as a dopant. The primary analytical techniques include high-resolution transmission electron microscopy (for detailed structural studies), Raman spectroscopy (for structural, vibrational, and optical properties), atom probe tomography (for chemical composition mapping with sub-nm resolution) and field-effect transistor measurements (for electrical characterization, including the Fermi level position and carrier concentration and mobility). From a fundamental point of view, this research is enabling a better understanding of the interplay between the growth parameters (e.g., catalyst, growth temperature, dopant precursor) and the structural, morphological and electrical properties of SiC nanowires. From the applied point of view, the research is highlighting the key factors for synthesizing SiC nanowires with tailored doping for such applications as emitters for vacuum electronics, corrosion resistant charge storage devices, and other energy, sensing, and harsh environment applications. The project is providing core training for graduate and undergraduate students. A variety of outreach activities, including the participation of underrepresented students in research, are underway. The results of this work are being incorporated into talks given to the general public by the researchers and are also being widely disseminated through a variety of means such as refereed journals, conferences, lectures, and demonstration.
This project is co-funded by the Electronic and Photonic Materials (EPM) and Ceramics (CER) Programs in the Division of Materials Research (DMR).
