Wenjin Luo

Surface Plasmon‐Enhanced Photodetection in Few Layer MoS2 Phototransistors with Au Nanostructure Arrays

2D Molybdenum disulfide (MoS2 ) is a promising candidate material for high-speed and flexible optoelectronic devices, but only with low photoresponsivity. Here, a large enhancement of photocurrent response is obtained by coupling few-layer MoS2 with Au plasmonic nanostructure arrays. Au nanoparticles or nanoplates placed onto few-layer MoS2 surface can enhance the local optical field in the MoS2 layer, due to the localized surface plasmon (LSP) resonance. After depositing 4 nm thick Au nanoparticles sparsely onto few-layer MoS2 phototransistors, a doubled increase in the photocurrent response is observed. The photocurrent of few-layer MoS2 phototransistors exhibits a threefold enhancement with periodic Au nanoarrays. The simulated optical field distribution confirms that light can be trapped and enhanced near the Au nanoplates. These findings offer an avenue for practical applications of high performance MoS2 -based optoelectronic devices or systems in the future.

Arrayed Van Der Waals Broadband Detectors for Dual-Band Detection

An advanced visible/infrared dual-band photodetector with high-resolution imaging at room temperature is proposed and demonstrated for intelligent identification based on the 2D GaSe/GaSb vertical heterostructure. It resolves the challenges of producing large-scale 2D growth, achieving fast response speed, outstanding detectivity, and lower manufacture cost, which are the main obstacles for industrialization of 2D-materials-based photodetection.

Solution-Processed 3D RGO-MoS2/Pyramid Si Heterojunction for Ultrahigh Detectivity and Ultra-Broadband Photodetection

Molybdenum disulfide (MoS2 ), a typical 2D metal dichalcogenide (2DMD), has exhibited tremendous potential in optoelectronic device applications, especially in photodetection. However, due to the weak light absorption of planar mono-/multilayers, limited cutoff wavelength edge, and lack of high-quality junctions, most reported MoS2 -based photodetectors show undesirable performance. Here, a structurized 3D heterojunction of RGO-MoS2 /pyramid Si is demonstrated via a simple solution-processing method. Owing to the improved light absorption by the pyramid structure, the narrowed bandgap of the MoS2 by the imperfect crystallinity, and the enhanced charge separation/transportation by the inserted reduced graphene oxide (RGO), the assembled photodetector exhibits excellent performance in terms of a large responsivity of 21.8 A W-1 , extremely high detectivity up to 3.8 × 1015 Jones (Jones = cm Hz1/2 W-1 ) and ultrabroad spectrum response ranging from 350 nm (ultraviolet) to 4.3 µm (midwave infrared). These device parameters represent the best results for MoS2 -based self-driven photodetectors, and the detectivity value sets a new record for the 2DMD-based photodetectors reported thus far. Prospectively, the design of novel 3D heterojunction can be extended to other 2DMDs, opening up the opportunities for a host of high-performance optoelectronic devices.

Room-temperature single-photon detector based on single nanowire

Single-photon detectors that can resolve photon number play a key role in advanced quantum information technologies. Despite significant progress in improving conventional photon-counting detectors and developing novel device concepts, single-photon detectors that are capable of distinguishing incident photon number at room temperature are still very limited. We demonstrate a room-temperature photon-number-resolving detector by integrating a field-effect transistor configuration with core/shell-like nanowires. The shell serves as a photosensitive gate, shielding negative back-gated voltage, and leads to a persistent photocurrent. At room temperature, our detector is demonstrated to identify 1, 2, and 3 photon-number states with a confidence of >82%. The detection efficiency is determined to be 23%, and the dark count rate is 1.87 × 10-3 Hz. Importantly, benefiting from the anisotropic nature of 1D nanowires, the detector shows an intrinsic photon-polarization selection, which distinguishes itself from existing intensity single-photon detectors. The unique performance for the single-photon detectors based on single nanowire demonstrates the great potential for future single-photon detection applications.

Uncooled infrared photodetectors based on one-dimensional nanowires and two-dimensional materials

Low dimensional semiconductors have attracted enormous attention in recent years. Owing to the special dimension confinement, photodetectors based on low dimensional materials and their hybrid systems exhibit considerable performance at room temperature. This differs from traditional thin-film infrared photodetectors which require liquid nitrogen cooling. In this paper, we introduce uncooled photodetectors based on one dimensional (1D) nanowires, two-dimensional (2D) materials, 2D hybrid structures and 1D/2D heterostructures. We illustrate their working mechanisms and reveal the potential for practical infrared detection.

Recent progress on localized-field enhanced few-layer MoS 2 photodetector

MoS2 is a promising candidate material for high speed optoelectronic devices, but with low photoresponsivity. Recently, we reported a large enhancement of photocurrent response by coupling few-layer MoS2 with Au nanoparticles or periodic Au nanoarrays[1].