This Materials World Network project explores the growth, structure and physical properties of vertically strain-controlled nanocomposite (VSCN) systems in epitaxial thin film form. The proposed research opens the door to a brand-new avenue for lattice strain control in two-phase nanocomposites, whereby the nanocolumns control the strain vertically in one another, independent of the interface. The elimination of interface control in the VSCN systems allows much thicker strained films (>300 nm) to be grown compared to lateral heteroepitaxial systems and thus allows a whole range of novel functional device possibilities. This project involves extensive collaboration between Texas A & M University (Dr. Wang) and the University of Cambridge (Dr. Driscoll) in the United Kingdom.
The goal of this joint program is to grow and understand VSCN epitaxial films for novel applications. The objectives include: 1) to develop a set of guidelines for predicting possible 2-phase nancomposite systems; 2) to utilize complementary deposition techniques to grow films of the predicted systems; 3) to determine the factors which control the VSCN architectures; and 4) to demonstrate one or two single phase property enhancements or novel multifunctionalities. This interdisciplinary effort combines research expertise from both universities. Novel VSCN systems will first be explored using chemical vapor deposition, CVD (Cambridge) and then, pulsed laser deposition, PLD (Texas). Various characterization techniques, such as high resolution XRD (Cambridge) and TEM (combined with STEM and EELS compositional analysis, Texas), as well as electrical and magnetic property measurements, will be utilized to investigate the structural, and functional properties of these VSCN systems.
The intellectual merit of the proposed research is the fundamental understanding of vertical strain-control in VSCN systems, which allows growth of strained layers far in excess of the conventional critical thickness. The project will have broad impact by 1) offering international multidisciplinary training to the researchers involved in the program and 2) enhancing the materials science and engineering curricula at both universities. The research results will be quickly disseminated to a much broader audience by (a) involving high school teachers in this research project, (b) involving under-represented groups in materials science and engineering and (c) attracting high school students into Materials Science program through the outreach programs available at both universities.
