NRL Develops Novel Monolayer Ferroelectric Hybrid Structures

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Scientists during a U.S. Naval Research Laboratory (NRL), Materials Science and Technology Division, have demonstrated that a energy and bright combination of a photoluminescence issued from a singular monolayer of tungsten disulphide (WS2) can be spatially tranquil by a polarization domains in an adjacent film of a ferroelectric element lead zirconium titanate (PZT).

These domains are created in a PZT regulating a conductive atomic force microscope, and a photoluminescence (PL) is totalled in atmosphere during room temperature. Because a polarization domain wall breadth in a ferroelectric can be as low as 1-10 nm, this proceed enables spatial modulation of PL energy and a analogous conduit populations with energy for nanoscale resolution.

Domains consisting of electric polarization dipoles are created in a checkerboard settlement into a skinny film of lead zirconium titanate (PZT) with a conductive atomic force microscope, and imaged with a same instrument (left panel). Both energy and bright placement of a photoluminescence issued from a monolayer of tungsten disulphide (WS2) eliminated onto a PZT aspect is strongly modulated by these polarization domains (right panel). (U.S. Naval Research Laboratory)

Single monolayer transition steel dichalcogenides (TMDs) such as WS2 vaunt distinguished visual properties due to their approach rope gap. The dielectric screening is really low due to their dual dimensional (2D) character, and so their properties are strongly influenced by their evident environment, and can be mutated and tranquil by variations in internal assign firmness due to adsorbates or electrostatic gating. This has generated penetrating seductiveness in a far-reaching accumulation of electronic and visual device applications.

The NRL scientist used a conducting atomic force microscope to write polarization domains into a PZT film in a checkerboard pattern. In any domain, a polarization dipole points possibly adult out of a aspect craft or down into a aspect plane, and produces possibly certain or disastrous assign on a PZT surface, respectively. The group afterwards eliminated monolayer WS2 that they had grown by chemical fog deposition techniques onto a PZT film.

They found that a PL energy from a WS2 is high usually from a areas over domains in a PZT where a polarization dipole points out of a aspect plane, as shown in a adjacent figure. Further investigate suggested that a bright combination of a PL was also strongly influenced — a spectra from a “up” domains were dominated by neutral exciton contributions (a firm state of an nucleus and hole outset from Coulomb interaction), while those from a “down” domains were dominated by negatively charged exciton, or trion, contributions (an exciton with an additional electron).

“Fabricating these hybrid 2D/3D ferroelectric heterostructures enables one to purposefully pattern and allay adjacent populations of trions and neutral excitons, formulating parallel domains in any geometry of choice” records Dr. Berend Jonker, comparison scientist and principal investigator. Dr. Connie Li, lead author of a study, serve points out: “Because a FE domains can be rewritten with an atomic force microscope and are non-volatile, this enables spatial modulation of a TMD properties with nanometer scale resolution.”

The boon includes growth of TMD materials and hybrid 2D/3D heterostructures with new functionality applicable to a DoD mission, including ultra-low energy electronics, non-volatile visual memory and quantum mathematics for destiny DoD applications in information estimate and sensing. The investigate formula are reported in a Dec 4, 2016, emanate of ACS Omega (DOI: 10.1021/acsomega.6b00302), a open entrance biography of a American Chemical Society. The paper was also comparison as an ACS Editors’ Choice featured paper. The investigate group enclosed Dr. Connie Li, Dr. Kathleen McCreary, and Dr. Berend Jonker from a Magnetoelectronic Materials Devices Section in a Materials Science and Technology Division during NRL.

Source: NRL