Spin-orbitronic devices based on 2D Rashba Janus crystals as active materials

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Named after the two-faced Roman god one looking to the future while the other facing to the past, Janus crystals are new atomically thin materials having two different phases with different atomic arrangements. Theoretically these materials have extraordinary spintronic properties, to design and fabricate spin-based electronic devices instead of traditional charge-based transistors found in current computers. So far device fabrication has been restrictive due to limitations in sample preparation. This project aims to understand the spintronic properties of Janus layers and to integrate them into spin-based field-effect transistors and gating devices for next-generation electronic applications. The societal impacts will manifest through the introduction of a new generation of spintronic devices and lowering energy consumption in high-speed electronic devices. The project plans to integrate high school, undergraduate, and master’s students into an active research environment to create next-generation engineers and scientists. Career opportunities will be offered to underrepresented communities through research in an active laboratory environment and laboratory tours. Outreach activities include, involvement of K-12 students through ASU’s SCENE program.This project focuses on studying the device physics of two-dimensional (2D) Janus transition metal dichalcogenide materials to demonstrate high-performance spin-FETs, tunable spin-texture devices, ballistic spin transport FETs by equalizing the Rashba and Dresselhaus effects by external gating. The initial experiments will involve synthesis of epitaxial and excitonic grade 2D Janus layers of MoSSe, WSSe, WSTe, and others with tunable Janus fields, followed by an understanding of Schottky junctions on 2D Janus semiconductors by using ohmic contact of a variety of metals. In addition, high-performance spin-FET devices will be fabricated with channel engineering insulation and optimized gate-stacks. Materials will be characterized, and devices will be optimized for process-structure-performance relations to achieve the highest spin-FET performance. Efforts will focus on establishing the foundations for spin precession and spin transport, gate-tunable spin textures, and spin FET operation on 2D Janus Rashba layers. The project will seek ways to achieve ballistic spin-transport and manipulation of spin-texture by suppressing spin relaxation through the Dresselhaus-Rashba crossover phenomena. The successful completion of this project will establish the fundamental device physics of 2D Janus layers, demonstrate spin-FETs based on these 2D Rashba Janus layers, and estswblish the basis for high-temperature scattering-resistant spin-FET operation through an interplay between Rashba-Dresselhaus terms.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.