【摘要】 采用基于第一性原理的密度泛函理论研究了四角晶相二氧化铪(t-HfO2)体相及其(001)表面的原子几何与电子结构.理论计算结果表明,t-HfO2(001)表面不会产生重构现象.与体相电子结构相比,t-HfO2(001)表面态密度明显高于体相态密度.其次,表面原子的态密度更靠近费米能级(EF),价带往低能量处移动,并有表面态产生.计算结果表明了t-HfO2表面禁带宽度明显低于体相的禁带宽度.t-HfO2(001)的表面态产生以及表面禁带宽度减小是由于Hf原子与O原子的配位数减少,表面原子周围的环境发生变化而引起的.更多还原

【Abstract】 The geometries and the electronic structures of t-HfO-2 and its (001) surface have been studied by first-principle calculations using the density functional theory (DFT). The optimized results show that the t-HfO-2 (001) surface has no surface reconstruction. Compared with the bulk electronic structure, the density of states (DOS) of t-HfO-2 (001) surface is higher than that of the bulk. In addition, the DOS of t-HfO-2 (001) surface is closer to the Fermi level. The valence band has the tendency to move toward the lower energy, resulting in the formation of a new surface state. The band gap of t-HfO-2 (001) surface is much smaller than that of bulk band gap. The existence of a new surface state and the reduction of band gap are due to the reduction of the Hf and O surface coordination which are different from the bulk atoms.更多还原