The Band,Electronic Structure And Optical Properties Of Monolayer Black Phosphorus Regulated By Uniaxial Strain And Doped By La Atoms

Monolayer black phosphorus（BP）is a unique two-dimensional material,with excellent electrical conductivity,such as high conductivity,high mobility and high switching ratio.It exhibits significant in-plane anisotropy,stable structure and a variety of preparation methods.These properties make monolayer BP display more development potential than other two-dimensional materials in device applications,with broader application prospect.By means of the first-principles method,the band structure,electronical and optical properties of monolayer black phosphorus regulated by uniaxial strain as well as doped by La atoms are systematically investigated and analyzed.The results are as follows:1.Uniaxial strain can change the band structure of BP,and effectively adjust the band gap within the range of 0 e V～1.346 e V.When the X axis is subjected to 10%compressive strain,the monolayer BP becomes metallic material.The image of optical properties is red shifted when BP is at tensile strain.Under compressive strain,the blue shift behaviors occur for monolayer BP.The static reflectance can be regulated by uniaxial strain in the range of 0.1～0.13,and the reflectance is up to 83%.The static refraction index of BP can be regulated by uniaxial strain in the range of 1.93～2.23,and the peak value of refraction index can be up to 2.46.The static dielectric function can be regulated in the range of 3.75～4.96.2.As for the electronic structure of BP doped with different La atoms concentrations,it reveals that most of La-doped BP exhibit direct band gap,in addition to La₃P.Besides,the energy gap decreases monotonically with the increase of doping concentration.The maximum energy gap is 1.024 e V when the La-doped concentration is 1/32.The minimum energy gap is0.541 e V with BP doped by La atoms 1/4 concentration.If the doping concentration continues to increase,it may approach the gap of bulk BP.Compared with pure BP,the reflectance,refractive index and loss function peaks of P₃₁La system become larger,and the image is red shifted. However,the absorption peak,extinction coefficient and conductivity peak decrease.On the other hand,the peaks of optical properties of P₁₅La,P₇La and P₃La systems all increase.In other words,in P₁₅La system,the reflectance and loss function exhibit the maximum value.In P₇La system,the real part of refractive index,extinction coefficient and dielectric function have maximum values.The absorption rate and conductivity of P₃La system have the maximum value.After La doped,the coverage of optical properties of the system is increased.