CAREER: Understanding polar surfaces and interfaces using ultra-high resolution electron microscopy and spectroscopy

North Carolina State University, Raleigh NC

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: This CAREER award supports an integrated research and education effort that advances the understanding of material interfaces essential to enable next generation electronics. Formation of interfaces between certain dissimilar materials results in unique properties that lead to new electronic device functionality. The detailed arrangement and bonding of atoms at these interfaces is intimately linked to the observed behavior. Recent advancements in electron microscopy have enabled the investigation of these arrangements at an incredible level. This project employs these state-of-the-art electron microscopy methods to directly study the interface structure and bonding to offer a fresh perspective on these phenomena, providing input to validate theoretical models. To drive student passion in science and engineering, the project is coupled to a variety of targeted educational programs. Undergraduate students directly contribute to the project by building computer programs that facilitate new approaches to microscopy education. Moreover, because traditional approaches to bring new students into science have only been partially successful, the centerpiece of the educational outreach program stimulates interest in science through the combination of microscopy with the visual arts. For the broadest impact among young students and the general public, this exhibit is distributed through connections with a local museum and the NSF Nanoscale Informational Science Education network. This project stands to increase the U.S. innovation and economic competitiveness in the area of electroceramics and through advances in characterization techniques. TECHNICAL DETAILS: This CAREER award addresses the fundamental nature of structural and electronic reconstructions at the interface between distinctly different polar materials and their surfaces. In particular, rock salt oxides are combined with wurtzite nitrides to explore the details of charge compensation mechanisms at heterogeneous polar interfaces. The influence of strain and defects on the electronic and atomic structure at the interface is examined with state-of-the-art electron microscopy tools. Moreover, in situ electron microscopy is used to study the stability and structure of the rock salt oxides to provide critical input relevant to growth, integration, and control of this class of materials. Simultaneously, electron microscopy capabilities are being developed to fully extract the detailed atomic/electronic structure and chemistry at the polar interfaces. The results also guide and validate modeling from ab-initio calculations that lead to transformational understanding of unique behaviors. Broader impacts and educational outreach are integral to this effort. Students at the graduate level become skilled experts of ultra-high resolution electron microscopy and spectroscopy using state-of-the-art instrumentation. Undergraduate students participate through a programming project to develop a 'digital' microscope to transform microscopy education in the age of aberration correction. Working with local museums and schools, an exhibit communicates advanced electron microscopy and materials science research through the universal medium of art, highlighting the inherent beauty of atomic structure symmetries.