空位缺陷对CrSi_2光电性能的影响

采用第一性原理方法,计算含空位缺陷CrSi2的电子结构和光学性质,并分析含Cr和Si空位缺陷的CrSi2光电性能.结果表明:Cr和Si空位均使CrSi2的晶格常数和体积变小;能带结构密集而平缓,且整体向上移动,Si空位缺陷形成带隙宽度为0.35eV的p型间接带隙半导体,Cr空位缺陷在原禁带间出现两条新的能带;含空位缺陷CrSi2的电子态密度仍主要由Cr3d层电子贡献,Si空位缺陷对电子态密度的影响较小,Cr空位缺陷提高了Fermi面处的电子态密度;与CrSi2相比,含空位缺陷CrSi2的介电峰均向低能方向略有偏移且峰值降低,吸收系数明显变小.

Optical-Electrical Characteristics of CrSi2 with Vacancy Defect

The electronic structure and optical properties of CrSi₂ with vacancy defect were calculated based on the first principles method, and the photoelectric properties of CrSi₂ with Cr or Si vacancy defect were analyzed. The results show that the lattice constants and volume are all decreased with Cr or Si vacancy defect. The band structure becomes intensive and gentle, and moves upward. The band structure of CrSi₂ with Si vacancy defect isp type indirect semiconductor with a band gap of 0.35 eV; while two new energy levelsare induced in the forbidden band with Cr vacancy defect. Density of states of
the valence band top and conduction band bottom are mainly composed of Cr 3d. Si vacancy defect has a little effect on the density of states; Crvacancy defect improves the density of states of the Fermi energy. Compared with that of pure CrSi₂, the dielectric peak slightly moves to the lower energy and decreases with vacancy defect, and the absorption index obviously decreases.