表面修饰对硅锗合金纳米线的内部键长分布及能带影响的机理研究

采用密度泛函第一性原理方法,研究了三种不同官能团修饰对硅锗111方向纳米线内部键长分布的不均匀性及能带影响,计算结果表明CH_3修饰加剧了键长分布不均性,与其它两个官能团相比,键长峰值弱化,键长范围扩大,也就是键长发生了再分布,F修饰对键长表现出了拉力效应,但并没有引起键长的再分布.同时,通过计算电子性质,以H修饰纳米线为参考,因不同官能团修饰对键长不均匀性的影响不同,使能带Z点位置下移幅度不同,CH_3修饰纳米线下移幅度最大,F次之,H修饰的下移幅度最小,这为利用不均匀性调控电子结构提供了理论依据.

Influence of Various surface passivations on bond length and band structure for Si-Ge alloy nanowires

The effect of three various surface passivations on the <111> orientation Si-Ge alloy nanowires` structural inhomogeneity was studied by the first principle. The calculated results show that CH3 surface passivation aggravates the structure inhomogeneity and leads to the bond length redistributed. The F modification shows the tensile stress response to the bond length, without causing the redistribution of the bond length. Moreover, the effects of different functional group modifications on the intrinsic inhomogeneity are different by calculating the electron density and using H modified nanowires as reference, which lead the Z point position of the energy band to move down differently. CH3 surface passivation makes the maximum Z point down. These conclusions could provide a theoretical reference for the use of inhomogeneity to regulate the electronic structure of Si-Ge alloy nanowires.