Room Temperature, Twist Angle Independent, Momentum Direct Interlayer Excitons in van der Waals Heterostructures with Wide Spectral Tunability.

Interlayer excitons (IXs) in van der Waals heterostructures with static out of plane dipole moment and long lifetime show promise in the development of exciton based optoelectronic devices and the exploration of many body physics. However, these IXs are not always observed, as the emission is very sensitive to lattice mismatch and twist angle between the constituent materials. Moreover, their emission intensity is very weak compared to that of corresponding intralayer excitons at room temperature.

Low Power Volatile and Nonvolatile Memristive Devices from 1D MoO-MoS Core-Shell Heterostructures for Future Bio-Inspired Computing.

Memristors-based integrated circuits for emerging bio-inspired computing paradigms require an integrated approach utilizing both volatile and nonvolatile memristive devices. Here, an innovative architecture comprising of 1D CVD-grown core-shell heterostructures (CSHSs) of MoO-MoS is employed as memristors manifesting both volatile switching (with high selectivity of 10 and steep slope of 0.6 mV decade) and nonvolatile switching phenomena (with I/I ≈10 and switching speed of 60 ns).

Observation of positive trions in α-MoO/MoS van der Waals heterostructures.

Mono-layer transition metal dichalcogenides (TMDCs) have emerged as an ideal platform for the study of many-body physics. As a result of their low dimensionality, these materials show a strong Coulomb interaction primarily due to reduced dielectric screening that leads to the formation of stable excitons (bound electron-hole pairs) and higher order excitons, including trions, and bi-excitons even at room temperature. van der Waals (vdW) heterostructures (HSs) of TMDCs provide an additional degree of freedom for altering the properties of 2D materials because charge carriers (electrons) in the different atomically thin layers are exposed to interlayer coupling and charge transfer takes place between the layers of vdW HSs.

Anomalously polarised emission from a MoS/WS heterostructure.

We report circularly polarised emission, with helicity opposite to the optical excitation, from a van der Waals heterostructure (HS) consisting of a monolayer MoS and three-layer WS. Selective excitation of the MoS layer confirms that this cross-polarized emission is due to the charge transfer from the WS layers to the MoS layer. We propose that the high levels of n-doping in the constituent layers due to sulphur vacancies and defects give rise to an enhanced transition rate of electrons from the valley of WS to the ' valley of MoS, which leads to the emission, counter polarized to the excitation.

Symmetric domain segmentation in WSflakes: correlating spatially resolved photoluminescence, conductance with valley polarization.

The incidence of intra-flake heterogeneity of spectroscopic and electrical properties in chemical vapour deposited (CVD) WSflakes is explored in a multi-physics investigation via spatially resolved spectroscopic maps correlated with electrical, electronic and mechanical properties. The investigation demonstrates that the three-fold symmetric segregation of spectroscopic response, in topographically uniform WSflakes are accompanied by commensurate segmentation of electronic properties e.g.

Twist-Dependent Tuning of Excitonic Emissions in Bilayer WSe.

Monolayer (ML) transition metal dichalcogenides (TMDCs) have been rigorously studied to comprehend their rich spin and valley physics, exceptional optical properties, and ability to open new avenues in fundamental research and technology. However, intricate analysis of twisted homobilayer (t-BL) systems is highly required due to the intriguing twist angle (t-angle)-dependent interlayer effects on optical and electrical properties. Here, we report the evolution of the interlayer effect on artificially stacked BL WSe, grown using chemical vapor deposition (CVD), with t-angle in the range of 0 ≤ θ ≤ 60°.

High degree of circular polarization in WS spiral nanostructures induced by broken symmetry.

We present helicity resolved photoluminescence (PL) measurements of WS spiral (SPI) nanostructures. We show that very high degree of circular polarization (DCP) (~94 ± 4%) is obtained from multilayer SPI samples at room temperature upon excitation with a circularly polarized laser at a wavelength near-resonant with the A-exciton (633 nm). TEM analysis showed that these SPI nanostructures have AB stacking in which the inversion symmetry is broken, and hence this leads to very high DCP.