表面合金化对NiPt金属栅电极功函数的影响

Effect of Surface Alloying on Work Function of NiPt Metal Gate

利用基于密度泛函理论的第一性原理方法研究了Ni1-xPtx(111)和Ni1-xPtx(001)表面合金的功函数.计算结果表明,Pt原子掺杂在表面层时对功函数影响较大,而且表面层Pt原子掺杂后的合金结构最为稳定;对于Ni1-xPtx(001),当表面层Pt原子的覆盖度从0增加到100%时,功函数近线性增加了0.6eV;而对于Ni1-xPtx(111),当表面层Pt原子的覆盖度从0增加到25%时,功函数增加了0.22eV,覆盖度从25%增加到100%时,功函数却几乎不再变化.上述结果表明,表面层合金化对功函数有重要影响,而金属功函数又强烈依赖于表面取向.

Work functions of Nil-xPtx （111） and Nil-xPtx （001） surface alloys with differ- ent compositions are investigated using first-principles methods based on density-functional theory. Results of calculations reveal that Pt doping in the surface layer has a significant ef- fect on the work function and the alloy with Pt-doped in the surface layer is most stable. The work function of Nil-zPtx （001） surface increases linearly by as much as 0.6 eV when the surface coverage of Pt atoms increases from zero up to 100%, while that of Nil-xPtx （111） surface increases by only 0.22 eV when the surface coverage of Pt atoms increases from zero to 25%0 and hardly changes when the surface coverage of Pt atoms increases from 25% to 100%. The above results reveal that Surface alloying has a significant effect on the work function and the metal work function has strongly orientation dependence.