High-Throughput Growth of Hexagonal Boron Nitride Film Using Porous-Structure Isolation Layer

Chemical vapor deposition is considered as the most hopeful method for the synthesis of large-area high-quality hexagonal boron nitride on the substrate of catalytic metal. However, the size the hexagonal boron nitride films are limited to the size of growth chamber, which indicates a lower production efficiency. In this paper, the utilization efficiency of growth chamber is highly improved by alternately stacking multiple pieces of Cu foils and carbon fiber surface felt with porous structure. Uniform and continuous hexagonal boron nitride films are prepared on Cu foils through chemical vapor deposition utilizing ammonia borane as the precursor. This work develops a simple and practicable method for high-throughput preparation of hexagonal boron nitride films, which could contribute to the industrial application of hexagonal boron nitride. .

Preparation of meter-scale Cu foils with decimeter grains and the use for the synthesis of graphene films

Chemical vapor deposition(CVD)is the most promising method for the preparation of high-quality and large-area graphene films,especially the epitaxial growth of graphene on large-area single-crystal Cu foils.While single-crystal Cu foils are normally achieved by thermally annealing the commercial poly-crystalline Cu foils,their size and therefore the size of graphene films grown on them are limited to the size of the reaction chamber.We report a simple and feasible method to prepare large-area Cu foils with decimeter grains by thermally annealing the rolled-up Cu foils,where the Cu layers are separated by thin porous carbon fiber cloths.The carbon fiber cloths prevent Cu layers from sticking to each other at high temperatures while do not block the gas transportation.In such a way,the utilization efficiency of the reaction chamber is significantly improved,e.g.,0.2 m×(1e2)m Cu foils can be processed even in a 5 cm diameter quartz tube chamber.High-quality graphene films grown on such Cu foils are then demon-strated.This method may be suitable for the annealing of other metal foils to enlarge grain size and the synthesis of other two-dimensional materials on them such as h-BN.

Pressure-triggered stacking dependence of interlayer coupling in bilayer WS_(2)

Tungsten disulfide(WS_(2))has been reported to show negligible stacking dependence under ambient conditions,impeding its further explorations on physical properties and potential applications.Here,we realize efficient modulation of interlayer coupling in bilayer WS_(2)with 3R and 2H stackings by high pressure,and find that the pressure-triggered interlayer coupling and pressure-induced resonant-to-nonresonant transition exhibit prominent stacking dependence,which are experimentally observed for the first time in WS2.Our work may unleash the stacking degree of freedom in designing WS_(2)devices with tailored properties correlated to interlayer coupling.

Fano resonance-enhanced Si/MoS_(2) photodetector

In this work,a Si∕MoS_(2) heterojunction photodetector enhanced by hot electron injection through Fano resonance is developed.By preparing Au oligomers using capillary-assisted particle assembly(CAPA)on the silicon substrate with a nanohole array and covering few-layer MoS_(2) with Au electrodes on top of the oligomer structures,the Fano resonance couples with a Si∕MoS_(2) heterojunction.With on-resonance excitation,Fano resonance generated many hot electrons on the surface of oligomers,and the hot electrons were injected into MoS_(2),providing an increased current in the photodetector under a bias voltage.The photodetectors exhibited a broadband photoresponse ranging from 450 to 1064 nm,and a large responsivity up to 52 A/W at a wavelength of 785 nm under a bias voltage of 3 V.The demonstrated Fano resonance-enhanced Si∕MoS_(2) heterojunction photodetector provides a strategy to improve the photoresponsivity of two-dimensional materials-based photodetectors for optoelectronic applications in the field of visible and near-infrared detection.