CAREER: Rational Design of Ferroelectric Semiconductors

Washington University, Saint Louis MO

Investigators

Abstract

NONTECHNICAL SUMMARY This award supports theoretical, computational, and experimental research integrated with education to accelerate the discovery of a rare class of semiconductors and advance the understanding of their physical properties. Semiconductors, such as silicon, have conductivity between that of insulators and metals and are essential components of electronic devices used for information processing, solar cells, and light-emitting diodes. Typical electronic devices include one or more interfaces between alternating layers of the same semiconductor material to which either additional positively or negatively charged impurities have been added. These interfaces often reduce the efficiency of the electronic devices. This project aims to develop a class of semiconductors that can operate without the need for creating such interfaces. Such semiconductors, by virtue of their atomic structure, have a built-in electric field that can help move charges across them. Moreover, the direction of the flow of charges within such semiconductors can be switched by an external electric field. By eliminating the interfaces, this class of semiconductors is expected to enable the realization of significantly more effective and efficient devices with applications in energy generation and storage, information storage and processing, and others. The education and outreach activities of this project involve using Augmented Reality (AR) to vividly and clearly illustrate complex material structures and dynamical processes at the atomic level. These activities will be implemented as modules in undergraduate and graduate curriculum to jump-start students’ understanding of complex material structures and enhance retention of structure-property correlations. AR datasets will be disseminated through an online repository to enable widespread use at other institutions, energizing students about entering the field of materials science. TECHNICAL SUMMARY This award supports theoretical, computational and experimental research integrated with education to accelerate the development of ferroelectric semiconductors, a rare class of electronic materials that combine the properties of both semiconductors and ferroelectrics in a single material. The research will employ a combination of first-principles density-functional-theory calculations, group-theoretical methods, and materials informatics to predict new, stable, ferroelectric semiconductors with a wide range of properties that are inaccessible in either of the individual classes of materials. Those ferroelectric semiconductors that are predicted to have the most promising set of properties will be synthesized and their properties characterized through collaborations. Subsequently, the role of microstructure and composition on the functional properties will be evaluated using a combination of electron microscopy and density functional theory calculations. The education goal of this project is to engage, excite, and educate students about understanding and predicting properties of materials by knowing their atomic structure. This objective will be achieved through the development of augmented-reality (AR)-based atomic models of various material structures and dynamical processes, and their dissemination as modules to efficiently explain structure-property correlations. These modules will be implemented in various Materials Science courses at both the undergraduate and graduate levels, and will be made available online for use at other institutions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.