P-n junctions based on vertically stacked van der Waals (vdW) materials have attracted a great deal of attention and may open up unforeseen opportunities in electronics and optoelectronics. However, due to the lack of intrinsic p-type vdW materials, most previous studies generally adopted electrical gating, special electrode contacts, or chemical doping methods to realize p-n vdW junctions. GaTe is an intrinsic p-type vdW material with a relatively high charge density, and it has a direct band gap that is independent of thickness. Here, we report the construction of ultrathin and tunable p-GaTe/n-MoS2 vdW heterostructure with high photovoltaic and photodetecting performance. The rectification ratio, external quantum efficiency, and photoresponsivity are as high as 4 × 10(5), 61.68%, and 21.83 AW(-1), respectively. In particular, the detectivity is up to 8.4 × 10(13) Jones, which is even higher than commercial Si, InGaAs photodetectors. This study demonstrates the promising potential of p-GaTe/n-MoS2 heterostructures for next-generation electronic and optoelectronic devices.

www.advmat.de www.advancedsciencenews.com production challenging. Since the discovery of the chemical vapor deposition (CVD) method as a successful approach for the growth of graphene crystals, [53,54] the method has also been expanded to the preparation of other 2D layered materials. Currently, this approach has been extended to rationally design various 2D TMD materials, such as MoS 2 nanosheets, [55][56][57][58] MoSe 2 nanosheets, [59,60] WS 2 nanosheets, [61,62] ReS 2 nanosheets, [63] and some heterostructures, [64,65] which have sparkled several interesting chemical and electronic properties. Although various 2D TMDs have been successfully grown using a facile CVD method, the intrinsic growth mechanism and the batch production of wafer-scale films, conducive to the high-performance in electronics/optoelectronics and other fields, still need more exploration. Very recently, some important progress on the synthesis of 2D TMDs, multi-heterostructures and superlattices has been realized.Herein, we concentrate on the recent progress in the synthesis of 2D TMDs and related heterostructures via the CVD method. We start with the effects of some key factors such as temperature, carrier gas, and the ratio of precursors on the synthesis of 2D TMDs via CVD technique. Then we summarize the importance of the growth substrates and the growth system to large-scale synthesis. Hence, large-scale 2D TMDs have been obtained on the basis of properly designed CVD growth. Furthermore, some recent breakthroughs in the growth of new kinds of semiconducting and metallic 2D TMDs via the CVD technique are described. The fundamental electronic properties and unique physical phenomena emanating from high quality CVD-grown TMDs are also reviewed. Finally, the controlled growth of alloys with tunable band structures, different multiheterostructures with atomically sharp interfaces and superlattices from 2D TMD crystals is analyzed, which can offer further step for the synthesis of 2D crystals and provides significantly more material systems. Lastly, we emphasize a summary of this review and the future prospects of these materials.Recently, the CVD method has been widely regarded as a technique available for growing 2D atomic crystals. Various atomically thin layered MX 2 semiconductors, such as MoS 2 , [55,66,67] WS 2 , [68] MoSe 2 , [69] MoTe 2 , [70,71] etc., have been successfully achieved by the CVD method. Through in-depth research on the growth dynamics in the CVD system, several key factors in the growth process for obtaining a large-scale, uniform monolayer MX 2 have been explored. For example, triangular WS 2 flakes were synthesized on a sapphire substrate via a CVD system, and a detailed analysis of the controllable growth behavior was given. [61] The growth system is maintained at a very low pressure during the growth process via an operating pump, which provides a uniform flow of vapor precursors and is beneficial to the uniform growth. First, the distance between the source and substrate (D ss ) was discovered to be a vital fa...

BackgroundSub-therapeutic antibiotics are widely used as growth promoters in the poultry industry; however, the resulting antibiotic resistance threatens public health. A plant-derived growth promoter, Macleaya cordata extract (MCE), with effective ingredients of benzylisoquinoline alkaloids, is a potential alternative to antibiotic growth promoters. Altered intestinal microbiota play important roles in growth promotion, but the underlying mechanism remains unknown.ResultsWe generated 1.64 terabases of metagenomic data from 495 chicken intestinal digesta samples and constructed a comprehensive chicken gut microbial gene catalog (9.04 million genes), which is also the first gene catalog of an animal’s gut microbiome that covers all intestinal compartments. Then, we identified the distinctive characteristics and temporal changes in the foregut and hindgut microbiota. Next, we assessed the impact of MCE on chickens and gut microbiota. Chickens fed with MCE had improved growth performance, and major microbial changes were confined to the foregut, with the predominant role of Lactobacillus being enhanced, and the amino acids, vitamins, and secondary bile acids biosynthesis pathways being upregulated, but lacked the accumulation of antibiotic-resistance genes. In comparison, treatment with chlortetracycline similarly enriched some biosynthesis pathways of nutrients in the foregut microbiota, but elicited an increase in antibiotic-producing bacteria and antibiotic-resistance genes.ConclusionThe reference gene catalog of the chicken gut microbiome is an important supplement to animal gut metagenomes. Metagenomic analysis provides insights into the growth-promoting mechanism of MCE, and underscored the importance of utilizing safe and effective growth promoters.Electronic supplementary materialThe online version of this article (10.1186/s40168-018-0590-5) contains supplementary material, which is available to authorized users.