Electrical spectroscopy of defect states and their hybridization in monolayer MoS.

Defects in solids are unavoidable and can create complex electronic states that can significantly influence the electrical and optical properties of semiconductors. With the rapid progress in the integration of 2D semiconductors in practical devices, it is imperative to understand and characterize the influence of defects in this class of materials. Here, we examine the electrical response of defect filling and emission using deep level transient spectroscopy (DLTS) and reveal defect states and their hybridization in a monolayer MOCVD-grown material deposited on CMOS-compatible substrates.

Disorder-induced bulk photovoltaic effect in a centrosymmetric van der Waals material.

Sunlight is widely seen as one of the most abundant forms of renewable energy, with photovoltaic cells based on pn junctions being the most commonly used platform attempting to harness it. Unlike in conventional photovoltaic cells, the bulk photovoltaic effect (BPVE) allows for the generation of photocurrent and photovoltage in a single material without the need to engineer a pn junction and create a built-in electric field, thus offering a solution that can potentially exceed the Shockley-Queisser efficiency limit. However, it requires a material with no inversion symmetry and is therefore absent in centrosymmetric materials.

Room-temperature electrical control of polarization and emission angle in a cavity-integrated 2D pulsed LED.

Devices based on two-dimensional (2D) semiconductors hold promise for the realization of compact and versatile on-chip interconnects between electrical and optical signals. Although light emitting diodes (LEDs) are fundamental building blocks for integrated photonics, the fabrication of light sources made of bulk materials on complementary metal-oxide-semiconductor (CMOS) circuits is challenging. While LEDs based on van der Waals heterostructures have been realized, the control of the emission properties necessary for information processing remains limited.

Engineering Optically Active Defects in Hexagonal Boron Nitride Using Focused Ion Beam and Water.

Hexagonal boron nitride (hBN) has emerged as a promising material platform for nanophotonics and quantum sensing, hosting optically active defects with exceptional properties such as high brightness and large spectral tuning. However, precise control over deterministic spatial positioning of emitters in hBN remained elusive for a long time, limiting their proper correlative characterization and applications in hybrid devices. Recently, focused ion beam (FIB) systems proved to be useful to engineer several types of spatially defined emitters with various structural and photophysical properties.

Superconducting 2D NbS Grown Epitaxially by Chemical Vapor Deposition.

Metallic two-dimensional (2D) transition metal dichalcogenides (TMDCs) are attracting great attention because of their interesting low-temperature properties such as superconductivity, magnetism, and charge density waves (CDW). However, further studies and practical applications are being slowed down by difficulties in synthesizing high-quality materials with a large grain size and well-determined thickness. In this work, we demonstrate epitaxial chemical vapor deposition (CVD) growth of 2D NbS crystals on a sapphire substrate, with a thickness-dependent structural phase transition.

Observation of Thermal Spin-Orbit Torque in W/CoFeB/MgO Structures.

Coupling of spin and heat currents enables the spin Nernst effect, the thermal generation of spin currents in nonmagnets that have strong spin-orbit interaction. Analogous to the spin Hall effect that electrically generates spin currents and associated electrical spin-orbit torques (SOTs), the spin Nernst effect can exert thermal SOTs on an adjacent magnetic layer and control the magnetization direction. Here, the thermal SOT caused by the spin Nernst effect is experimentally demonstrated in W/CoFeB/MgO structures.

Probing magnetism in atomically thin semiconducting PtSe.

Atomic-scale disorder in two-dimensional transition metal dichalcogenides is often accompanied by local magnetic moments, which can conceivably induce long-range magnetic ordering into intrinsically non-magnetic materials. Here, we demonstrate the signature of long-range magnetic orderings in defective mono- and bi-layer semiconducting PtSe by performing magnetoresistance measurements under both lateral and vertical measurement configurations. As the material is thinned down from bi- to mono-layer thickness, we observe a ferromagnetic-to-antiferromagnetic crossover, a behavior which is opposite to the one observed in the prototypical 2D magnet CrI.