气体在Si(111)面吸附的密度泛函研究

The Studies of Gases Adsorption on Si(111) Surface by Density Function Theory

运用广义梯度密度泛函理论(GGA)的PBE方法结合周期平板模型,计算了SiCl4,SiHCl3,H2,HCl在Si(111)表面的垂直吸附能和吸附结构。发现SiCl4,SiHCl3和Si衬底表面原子间的吸附结构不稳定,相比之下SiCl4,SiHCl3分子都容易吸附在凸起的Si原子上。衬底对SiHCl3的吸附能要大于对SiCl4的。SiCl4和SiHCl3分子断开1个Si Cl键后更容易吸附在Si(111)表面的悬挂键上。H2在Si(111)表面的2个位置的吸附能比较接近,HCl倾向于以H端吸附在电荷多的表面硅原子上。Si(111)表面对HCl的吸附能最大,当产物HCl出现后,其在Si(111)表面表面的脱附将成为反应的控制步骤。

The adsorptions of SiCl4,SiHCl3,H2,HCl molecules on Si(111) surface are studied with periodic slab model by Perdew-Burke-Ernzerh approach of GGA within the framework of density functional theory.The results show: The structures of SiCl4,SiHCl3 molecules on Si(111) surface are unstable,SiCl4 and SiHCl3 are easier to adsorb on the atoms which buckled-up on the surface.The absorption energys of SiHCl3 on the surface of the two positions are stronger than these of SiCl4's.It is easier to adsorb on the surface hanging bond when SiCl4 and SiHCl3 dissociate a Si-Cl bond.The absorption energies of H2 in two locations on the Si(111) surface are similar.The stabler absorption structure of HCl is H-side near silicon atoms which dent on the surface.There is the highest adsorption energy on the surface of Si(111) to HCl.When the product HCl generated,the desorption of HCl from the Si(111) surface will be the control step of the whole reaction.