用密度泛函理论研究氮化硅新相的电子结构、光学性质和相变  

Phase transition, electronic and optical properties of Si_3N_4 new phases at high pressure with density functional theory

作　　者：余本海[1] 陈东[1] 

机构地区：[1]信阳师范学院物理电子工程学院,信阳464000

出　　处：《物理学报》2014年第4期260-265,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:U1204501;11105115;11304141);河南省科技计划(批准号:112300410021);河南省教育厅科学技术研究重点项目(批准号:12A140010)资助的课题~~

摘　　要：运用第一性原理赝势方法,对氮化硅新相(六方Pˉ6和Pˉ6′相)的电子结构、光学性质和相变过程进行分析,研究能带结构、介电函数谱、反射谱和能量损失函数的变化机理.研究发现,β→Pˉ6→δ相变是可行的,在室温下β→Pˉ6和Pˉ6→δ相变的临界压强分别为42.9和47.7 GPa;相界的斜率为正值表明Pˉ6→δ相变过程伴随着晶胞体积的塌缩;Pˉ6和Pˉ6′相分别属于直接带隙和间接带隙半导体,能隙宽度分别为4.98和4.01 eV;得到了两相的零频介电常数;反射谱表明,两相的强反射峰均位于真空紫外线区域,因此可以用作紫外光屏蔽或紫外探测材料;在可见光区域,两相表现为近似透明.Characteristics of the hexagonal polymorph Si3N4 i.e., phase transition, electronic and optical properties （band structure, dielectric function, reflectivity and energy loss function） are investigated by the first-principles pseudo-potential method. The results suggest that it is feasible that the β→P6→δ transition takes place at room temperature. The critical pressures of the β→P6 and P6→δ transformations are 42.9 and 47.7 GPa, respectively. The phase transition from P6→δ is accompanied by the volume shrinkage. The calculated results also show that the P6 and p6＇ phases belong to direct bandgap and indirect bandgap semiconductors, respectively. The calculated band gaps are 4.98 and 4.01 eV for the P6 and p6＇ phases, respectively. Besides, the static dielectric constants are also obtained. The reflectivity shows that the two phases can serve as the shielding and detecting devices for ultraviolet radiation and they have optical transparent behaviors in the visible light region.

关 键 词：密度泛函理论 氮化物 光学性质 能带 

分 类 号：O469[理学—凝聚态物理]