First-principles calculation of two-dimensional MoSi2N4 doped with transition metals W,Mn,V and Ti
The changes in the geometric structure,electrical structure,and optical characteristics of the substitu-tion-doped MoSi2N4 crystal with W,Mn,V,and Ti were estimated using the fundamental principles of density functional theory(DFT).According to the electronic structure study,the prohibited band widths for W,Mn,W,and Ti doped two-dimensional MoSi2N4 are 1.806 eV,1.003 eV,1.218 eV,and 1.373 eV,respectively.Given that the doping structure is a p-type semiconductor and that the impurity energy level is the dominant en-ergy level,the impurity energy level introduced by W doping is close to the top of the valence band.Since the Fermi energy level and the impurity energy level are both near to the conduction band bottom and the doping structure is an n-type semiconductor,the impurity energy level introduced by Mn doping is also known as the sender energy level.The Fermi energy level,which is a part of the recombination center,is close to the impurity energy levels brought about by V and Ti doping.The optical property analysis shows that in the energy interval of 2 eV～4 eV,the absorption wavelength of the W-doped structure is 336 nm and the system is red-shifted;the absorption wavelengths of the Mn-,V-and Ti-dopend systems are 320 nm,358 nm and 338 nm,respec-tively,and they are blue-shifted.
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