Among atomically thin two-dimensional (2D) materials, molybdenum disulfide (MoS2) is attracting considerable attention because of its direct bandgap in the 2H-semiconducting phase. On the other hand, a 1T-metallic phase has been revealed, bringing complementary application. Recently, thanks to top-down fabrication using electron beam (EB) irradiation techniques, in-plane 1T-metal/2H-semiconductor lateral (Schottky) MoS2 junctions were demonstrated, opening a path toward the co-integration of active and passive two-dimensional devices. Here, we report the first transport measurements evidencing the formation of a MoS2 Schottky barrier (SB) junction with barrier height of 0.13-0.18 eV created at the interface between EB-irradiated (1T)/nonirradiated (2H) regions. Our experimental findings, supported by state-of-the-art simulation, reveal unique device fingerprint of SB-based field-effect transistors made from atom-thin 1T layers.

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Specific anisotropic-atomic-structure of atom-thin black phosphorus causes the anomalous magnetic-field dependence of the Hall resistance, which opens doors to novel quantum phenomena and innovative two-dimensional atom-thin devices.

We demonstrate that broadband sum frequency generation (SFG) spectroscopy based on a partially incoherent supercontinuum light source can elucidate dark p-series excitons in monolayer WSe2 encapsulated between hexagonal boron nitride (hBN) slabs. The observed 2p exciton peak energy is a few meV higher than that predicted by the Rytova-Keldysh potential model, which is originated from the Berry phase effect. Interestingly, although the radiative relaxation of the 2p exciton is weaker, the 2p exciton peak is broader than the 1s and 2s peaks, which indicates its faster dephasing than the 1s and 2s excitons. Measuring the excitation intensity and temperature dependence, we clarified that this broader linewidth is not caused by excitation- or phonon-induced dephasing, but rather by exciton-electron scattering.

Among various atomically thin two-dimensional materials, molybdenum disulphide (MoS2) is attracting considerable attention because of its direct energy bandgap in the 2H-semiconducting phase. On the other hand, a 1T-metallic phase, which is very important for unique applications, has been created by various methods. Recently, we demonstrated the creation of in-plane 1T-metal/2H-semiconductor MoS2 lateral Schottky junctions by using electron beam irradiation techniques and revealed their unique electrical properties. Here, we report the optoelectronic measurements proving the formation of this few-layer MoS2 lateral Schottky junction. A large photocurrent is confirmed in the reverse bias voltage regime, while it decreases with increasing distance between an electrode placed on the 2H region and the 2H/1T junction. These results suggest a concentration of high electric field and rapid dissociation of photogenerated excitons at the few-layer lateral Schottky junction, which are beneficial for highly efficient photodetectors.