A new single-element layered two-dimensional semiconductor:black arsenic

The discovery of graphene,the first two-dimensional material with a thickness of an atomic layer,opened the prelude to the development of other atom-thin two-dimensional layered materials.They are considered to be one of the best candidates to extend Moore’s law.However,graphene is a zero-bandgap semimetal,which limits its application in logic circuits[1].

Two-dimensional noble transition-metal dichalcogenides for nanophotonics and optoelectronics:Status and prospects

An emerging subclass of transition-metal dichalcogenides(TMDs),noble-transition-metal dichalcogenides(NMDs),has led to an increase in nanoscientific research in two-dimensional(2D)materials.NMDs feature a unique structure and several useful properties.2D NMDs are promising candidates for a broad range of applications in areas such as photodetectors,phototransistors,saturable absorbers,and meta optics.In this review,the state of the art of 2D NMDs research,their structures,properties,synthesis,and potential applications are discussed,and a perspective of expected future developments is provided.

Alloying-engineered high-performance broadband polarized Bi_(1.3)In_(0.7)Se_(3)photodetector with ultrafast response

Topological insulators have important potential for applications in the field of nano/micro-optoelectronic devices.However,the large dark current seriously hinders the improvement of device performance.Alloying is an important means to control the physical properties of topological insulators.In this work,we have designed and prepared Bi_(1.3)In_(0.7)Se_(3)crystals.The optoelectronic properties of the individual Bi_(1.3)In_(0.7)Se_(3)nanowire-based photodetector are systematically investigated.The photodetector is very sensitive to broadband wavelength from solar-blind ultraviolet C(254 nm)to near-infrared(1,064 nm),showing superior optoelectrical properties with photoresponsivity of 241.3 A·W^(–1)and detectivity of 1.18×10^(12)Jones at 638 nm.Furthermore,the photodetector demonstrates ultrafast photoresponse characteristics with a photoresponse time of about 770 ns,which is 3 to 6 orders of magnitude lower than other compound semiconductors based on Bi or In reported so far.In addition,it also exhibits good polarization sensitivity in a broadband range from ultraviolet C(266 nm)to near-infrared(1,064 nm)and obtained the maximum dichroic ratio is 1.73 at 1,064 nm.Our results suggest that this platform creates new opportunities for the development of low-cost,high-sensitivity,high-speed,and broadband angle-sensitive photodetectors.

The Coulomb interaction in van der Waals heterostructures

The giant Stark effect(GSE) in a set of van der Waals(vdW) heterostructures is studied using first-principles methods. A straightforward model based on quasi-Fermi levels is proposed to describe the influence of an external perpendicular electric field on both band gap and band edges. Although a general linear GSE is observed, which is induced by the almost linear variation of the band edges of each layer in the heterostructures, when vdW heterostructures is subjected to small electric fields the variation becomes nonlinear. This can be attributed to the band offsets-induced interlayer charge transfer and resulted intraand inter-layer Coulomb interactions. Our work, thus offers new insight into the mechanism of the nonlinear GSE in vdW heterostructures, which is important for the applications of vdW heterostructures on nanoelectronic devices.