Design and Integration of a Layered MoS₂/GaN van der Waals Heterostructure for Wide Spectral Detection and Enhanced Photoresponse

Abstract

Molybdenum disulfide (MoS2) as a typical two-dimensional (2D) transition-metal dichalcogenide exhibits great potential applications for the next-generation nanoelectronics such as photodetectors. However, most MoS2-based photodetectors hold obvious disadvantages including a narrow spectral response in the visible region, poor photoresponsivity, and slow response speed. Here, for the first time, we report the design of a two-dimensional MoS2/GaN van der Waals (vdWs) heterostructure photodetector consisting of few-layer p-type MoS2 and very thin n-type GaN flakes. Thanks to the good crystal quality of the 2D-GaN flake and the built-in electric field in the interface depletion region of the MoS2/GaN p–n junction, photogenerated carriers can be rapidly separated and more excitons are collected by electrodes toward the high photoresponsivity of 328 A/W and a fast response time of 400 ms under the illumination of 532 nm light, which is seven times faster than pristine MoS2 flake. Additionally, the response spectrum of the photodetector is also broadened to the UV region with a high photoresponsivity of 27.1 A/W and a fast response time of 300 ms after integrating with the 2D-GaN flake, exhibiting an advantageous synergetic effect. These excellent performances render MoS2/GaN vdWs heterostructure photodetectors as promising and competitive candidates for next-generation optoelectronic devices.

Liquid metals: an ideal platform for the synthesis of two-dimensional materials

“…Two-dimensional (2D) metal oxides can be isolated through various liquid metal-based techniques, including printing (touch, 4 squeeze, 6,37 or blade print [40][41][42][43][44][45] techniques), liquid phase growth and exfoliation (including sonication 46 and bubbling 4,47,48 methods), and surface templated growth of materials on liquid metal surfaces. 49,50 The liquid metal printing processes may also be used to assist the synthesis of heterostructures which will be discussed later in this review.…”

“…Blade coating is another alternative to the touch-and squeeze-printing techniques. 40,44 Several studies have reported different ways to perform this method, including brushing, 41 tape printing, 42,43 and roll transfer. 45 Nevertheless, they share a similarity in concept whereby a liquid metal is being moved across the substrate and leaves behind an oxide skin which is only weakly attached to the parent liquid metal.…”

“…Next, by utilising PDMS as a stamp, the oxide is transferred onto a desired substrate. 42,43 Fig. 3(e-g) elucidate characterisations of 2D tape-printed Ga 2 O 3 sheet.…”

Flexible Image Sensors with Semiconducting Nanowires for Biomimic Visual Applications

“…[81][82][83] Compared with pure NW devices, hybrid heterostructure optoelectronic devices are composed of two types of materials with different functions have a larger spectral response range, faster response speed, better sensitivity, higher optical characteristics, and emission efficiency. [84][85][86][87][88] For example, Tian et al proposed a method for combining hydrothermal growth and thermal evaporation to synthesize branched heterostructures that are composed of ZnO branches and a ZnS backbone. [89] The dendritic ZnS-ZnO heterostructure can be easily transferred to the flexible poly(ethylene terephthalate) (PET) substrate to form a nanofilm network for UV detection.…”

Arrayed MoS2–In0.53Ga0.47As van der Waals Heterostructure for High‐Speed and Broadband Detection from Visible to Shortwave‐Infrared Light

“…[ 1–3,6,9–11 ] So, the various MoS 2 ‐based heterojunction devices have been demonstrated showing enhanced detection performances and broadened spectral range in MoS 2 /Si, MoS 2 /GaAs, MoS 2 /GaN, MoS 2 /black phosphorous, etc. [ 2,6,12,13 ] Although there are many reports regarding heterojunction PDs, most of the MoS 2 ‐based devices have shown only a slight extension of wavelength coverage to approximately 1100 nm of Si materials, whereas there are strong demands on wider‐spectral PDs beyond 1300 nm for future optical communications and broadband imaging. [ 14,15 ] To extend the cutoff wavelength, the introduction of 3D bulk materials, which can provide longer wavelength absorption would be quite promising approach while considering band alignment for efficient photocarrier extraction.…”