First-Principles Study Of The Photoelectronic Properties Of Hydrogenatedsilicene/Halogenated-Silicene Superlattices

Silicene has many excellent physical properties,and it has the advantage of being compatible with traditional silicon industry technology,and is considered to be one of the excellent candidate materials for highly integrated circuits and micro-nano optoelectronic devices in the future.However,the disadvantages of poor stability of silicene and too small band gap have always restricted its application in practical devices.At present,although some methods have been proposed to improve the properties of silicene,such as applied electric field,strain,cutting into nanoribbons,substrates,and chemical modification,etc.These methods have deficiencies and cannot solve the problem well.Therefore,the exploration of low-dimensional silicene nanomaterials with good environmental stability and excellent electronic properties and the effective control of the properties of these materials are the key issues for the practical application of silicene.In recent years,two-dimensional planar composite materials have attracted widespread attention.Theoretical and experimental studies have shown that planar composite materials are not only easy to regulate and control,but also have excellent properties not possessed by a single two-dimensional material.Based on the current theoretical and experimental research progress of two-dimensional planar composite materials and silicene,we adopt hydrogen atoms and halogen atoms to saturate silicene partitioned to obtain a hydrogenated-silicene/halogenated-silicene superlattices.Through the first-principles method,we systematically studied the structural properties,electronic properties,and optical properties of the hydrogenated-silicene/halogenatedsilicene superlattices.It was found that this new type of two-dimensional superlattice has better stability than silicene due to all dangling bonds are saturated.And there is almost no lattice mismatch at the interface compared with other hybrid structures.By analyzing its electronic properties,it is found that all superlattices are direct band gap semiconductors,and the size of the band gap can be effectively regulated by the width of hydrogenated silicene(or halogenated silicene).Moreover,this type of superlattice can separate electrons and holes,and obviously enhance the absorption of visible light by silicene.The top of the valence band and the bottom of the conduction band meet the potential energy conditions of water splitting and have the function of water splitting.Our research indicates that these superlattices are expected to be candidates for optoelectronic devices and photocatalysis.Considering that the imperfect interfaces may occur during the growth process of materials,we further studied the superlattices with missing interface adsorption atoms and irregular interface adsorption.The results show that some superlattices can exhibit magnetism when adsorption atoms are missing at the interface,and the magnetic moment mainly comes from the unadsorbed silicon atom.For the irregular adsorption of the interface,it is found that the irregular shape of the interface has little effect on the energy band structure of the superlattices.Furthermore,superlattices with two kinds of interface defects still have good light absorption capacity in the visible light range.