High-quality homogeneous junctions are of great significance for developing transition metal dichalcogenides (TMDs) based electronic and optoelectronic devices. Here, we demonstrate a lateral p-type/intrinsic/n-type (p-i-n) homojunction based multilayer WSe2 diode. The photodiode is formed through selective doping, more specifically by utilizing self-aligning surface plasma treatment at the contact regions, while keeping the WSe2 channel intrinsic. Electrical measurements of such a diode reveal an ideal rectifying behavior with a current on/off ratio as high as 1.2 × 106 and an ideality factor of 1.14. While operating in the photovoltaic mode, the diode presents an excellent photodetecting performance under 450 nm light illumination, including an open-circuit voltage of 340 mV, a responsivity of 0.1 A W–1, and a specific detectivity of 2.2 × 1013 Jones. Furthermore, benefiting from the lateral p-i-n configuration, the slow photoresponse dynamics including the photocarrier diffusion in undepleted regions and photocarrier trapping/detrapping due to dopants or doping process induced defect states are significantly suppressed. Consequently, a record-breaking response time of 264 ns and a 3 dB bandwidth of 1.9 MHz are realized, compared with the previously reported TMDs based photodetectors. The above-mentioned desirable properties, together with CMOS compatible processes, make this WSe2 p-i-n junction diode promising for future applications in self-powered high-frequency weak signal photodetection.

Size-controlled synthesis and size-dependent antibacterial activity of Cu2O nanoparticles with high efficiency for H2O2 evolution.

The thickness dependence of the chemical and physical properties is one fundamental characteristic shared by many twodimensional layered transition-metal dichalcogenides, including molybdenum disulfide (MoS 2 ). Recently, in order to expand the scope of applications of MoS 2 , surface functionalization has been employed to engineer its chemical and electrical properties for the purposes of drug delivery, photothermal therapy, gas sensing, and biosensing. Here, we report a facile method for controlled functionalization of MoS 2 fieldeffect transistors of a wide range of thicknesses with α-lipoic acid (LA). Atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) show evidence of chemical bonding. After functionalization, a significant increase of on current is observed in the MoS 2 transistors, caused by the enhancement of electronic mobility. The maximum increase of mobility can reach ∼100% for monolayer devices. The thickness dependence of the mobility enhancement is analyzed, and a theoretical model based on vacancy filling and charge impurity scattering is proposed to reveal the microscopic origin. These results provide new opportunities of controlling the electronic properties of MoS 2 by surface functionalization.

Precursors and catalysts play vital roles in chemical reactions. Considerable efforts have been devoted to the investigation of catalysts for graphene growth by chemical vapor deposition in recent years. However, there has been little research on precursors because of a lack of innovation in term of creating a controllable feeding method. Herein, we present a novel sustained and controlled release approach, and develop a convenient, safe, and potentially scalable feeding system with the assistance of matrix materials and a simple portable feeder. As a result, a highly volatile liquid precursor can be fed accurately to grow large‐area, uniform graphene films with optimal properties. This feeding approach will further benefit the synthesis of other two‐dimensional materials from various precursors.

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