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提出了基于第一性原理的密度泛函理论框架下的广义梯度近似投影缀加波赝势法,在结构优化的基础上采用平板模型计算了GaAs(110)表面单一吸附0.5 ML Cs元素、单一吸附0.5 ML O元素及0.5 ML Cs、0.5 ML O共吸附系统的特定吸附位、吸附系统总能及吸附系统的电子结构。吸附系统总能的计算结果对比及电子结构图表明:当Cs、O元素吸附量在GaAs(110)表面达到Θ=1 ML时,它们并非各自在表面形成局域畴形态的竞争性共化学吸附,而是将在表面形成混合均匀相的协同共化学吸附。采用偶极子校正进一步计算三种吸附系统的功函数分别是4.423 e V、5.749 e V、4.377 e V,从而得出GaAs光电阴极制备过程中提高并保持光电阴极发射性能的方法及机理。
Based on the first principle, the generalized gradient approximate pseudorandom method of impinging on the GaAs (110) surface was calculated on the basis of the structural optimization. The single-site adsorption of 0.5 ML Cs on GaAs (110) 0.5 ML O element and 0.5 ML Cs, 0.5 ML O co-adsorption system, the total adsorption energy and the electronic structure of the adsorption system. Comparison of the calculated results of the total energy of the adsorption system and the electronic structure map shows that when the amount of Cs and O adsorbed on the surface of GaAs (110) reaches Θ = 1 ML, they are not competing co-chemisorptions each forming a localized domain morphology on the surface , But a synergistic chemisorption that will form a homogeneous mixture on the surface. The work function of the three adsorption systems calculated by dipole correction is 4.423 eV, 5.749 eV and 4.377 eV, respectively. The method and mechanism of improving and maintaining the emission performance of GaAs photocathode were obtained.