稀土（Sc, Y, La）掺杂CdS光电性质的第一性原理研究

采用第一性原理赝势平面波方法对CdS掺杂稀土元素(Sc、Y、La)的光电性质进行了计算与分析.计算结果表明:Sc、Y、La掺杂后,CdS的晶格常数增大,晶胞体积也相应增大.Sc、Y、La置换Cd导致费米面进入导带中,禁带宽度有所增大,导电类型变为n型,说明稀土Sc、Y、La是n型掺杂剂.稀土原子Sc、Y、La在费米能级处提供了额外的载流电子,对CdS的电子结构起到了改善作用.稀土原子的引入,增强了稀土原子与相邻S原子的相互作用,且稀土原子与S成键都有很高的共价性.稀土掺杂后CdS的静态介电常数、吸收系数和反射率都明显降低,表明其导电性和光的透过率增强.以上结果说明稀土元素的掺入能有效调制CdS的光电性质.

First principle study on photoelectric properties of CdS with doping rare earth(Sc, Y, La)

By using the first principle pseudo-potential plane-wave method, the photoelectric properties of CdS doped with rare earth (Sc, Y, La) are calculated and analyzed. The calculation results show that: after Sc, Y, La doped, the lattice constants increase, the cell volume also expands. When Sc, Y or La substitutes for Cd, the Fermi energy moves to conduction bands, the band gap widens, the conductivity type is changed into n-type. These indicate that Sc, Y, La is a n-type dopant. The atoms of Sc, Y, La generate a large number of additional carriers near the Fermi energy level in order to improve the electronic structure. Rare earth atoms and the neighboring S atoms form a stronger interreaction and hence a higher covalent banding after incorporation of rare earth. After rare earth doped, the static dielectric constant, absorption coefficient and reflectivity decrease significantly, indicating that the conductivity and transmission increase. These results indicate that rare earth can effectively modulate the photoelectric properties of CdS.