掺铝3C-SiC电子结构的第一性原理计算及其微波介电性能

摘要

采用基于密度泛函理论的第一性原理平面波超软赝势法，对比研究了未掺杂和Al掺杂3C-SiC材料的电子结构和介电常数．结果表明：Al掺杂后，Fermi能级进入价带，带隙宽度略为加宽，在8．2-12．4GHz范围内介电常数大幅度增大．利用燃烧合成法制备了Al掺杂的3C-SiC粉体吸收剂，通过矢量网络分析仪测试了样品在8．2-12．4GHz范围内的微波介电常数，验证了理论计算结果，并讨论了微波损耗机理．%The electronic structure and permittivity of Al-doped 3C-SiC are studied by using the first principles plane-wave pseudopotential method based on the density functional theory, and compared with those of undoped 3C-SiC. Results show that the Fermi energy level introduced into valence band and band gap is slightly widened through AI doping for 3C-SiC, and that the permittivity is greatly improved in a frequency range of 8.2-12.4 GHz. A1 doped 3C-SiC powder absorber is prepared by combustion synthesis, and the permittivities of the samples are measured in the frequency range of 8.2-12.4 GHz by vector network analyzer, which validates the results of theoretical calculation. The mechanism of microwave loss is discussed.