Nonvolatile ferroelectric memories, based on electrically switchable polarization, have been in mass production for over 20 years with a market size estimated to be in the hundreds of millions of dollars per year. However, a number of challenges, such as scaling issues, high operating voltages, relatively slow speed and structural degradation, limit further development of this technology and call for fundamental advances in materials science and device engineering. In this project, the principal investigators study hybrid heterostructures comprising ferroelectric perovskites and two-dimensional (2D) electronic materials, namely transition metal dichalcogenides. 2D electronic materials - the most notable among them being graphene - have recently attracted an unprecedented interest due to their unique physical and chemical properties. A combination of 2D and ferroelectric materials results in heterostructures with promising electronic and memory properties. Reversal of ferroelectric polarization direction allows modulation of the electrical conductivity of a 2D material, which provides a basis for the development of memory devices with superior characteristics, such as low power consumption and better scalability. This project will identify promising materials combinations for implementation in operational electronic memories and logic devices. The enhances science and engineering education at both undergraduate and graduate level. Within this research, a new nanotechnology laboratory course for undergraduate and graduate students is developed along with the outreach activities targeting K-12 students and their parents, teachers, minorities and underrepresented groups.
main scientific objective of the proposed research is implementation of the electronic devices comprising 2D materials and ferroelectric (FE) thin films that will exhibit polarization-controlled non-volatile modulation of the electronic transport. This project primarily focuses on 2D crystals of transition metal dichalcogenides, such as MoS2 and WS2. Polarization reversal is employed to modulate (1) the in-plane transport in a conducting channel of a field-effect transistor device, and (2) the perpendicular-to-plane tunneling conductance across the FE barrier. A critical component of this research is investigation of the effect of engineered molecular layers at the 2D-FE interfaces on the functional properties of these devices. The 2D materials, which are impermeable for gases and liquids, are used to trap and stabilize any molecular layer on a ferroelectric surface serving as effective cover layers for encapsulation of molecular species at the 2D-FE interface and providing a simple and straightforward method for interface engineering. This research will advance the fundamental understanding of the electronic properties of hybrid ferroelectric-based devices, build a lasting basis for the exploitation of controllable electronic barriers and channels, impact a broad range of physical phenomena from solid-state phase transitions to surface electrochemical reactions and contribute to technological development of nanoscale electronics.
