碳化硅纳米带“品”型器件的第一性原理研究

First-principles investigations on twist-shaped device based on silicon carbide nanoribbons

文章基于锯齿形碳化硅纳米带,通过将中间部分结构在空间上进行向上平移,再翻转180°形成异质结,保留碳边缘通道,形成“品”型三端异质结器件,并利用密度泛函理论和非平衡格林函数的计算方法,研究该三端器件的电子输运特性。计算结果表明:无论是在铁磁态还是反铁磁态下,一种自旋电子都能从一端电极经由异质结单边通道渡越到另一端电极,实现了100%的自旋极化电子输运;当对中心区外加栅压时,电流随着栅压增加而减小,当栅压大于0.5 V时,器件内部电子输运通道关闭,2种自旋电子均不能通过三端器件,表明通过栅极电压可以实现对器件内部电子输运能力的调控;若器件受到外力产生形变,只要形变量小于6.7%,电子输运能力几乎不改变。研究结果为基于碳化硅纳米带的纯自旋流器件的设计提供了有力的理论依据。

In this paper,the structure is based on zigzag silicon carbide nanoribbons(ZSiCNRs),with the middle section translating upward spatially and then flipping 180°.Thus,a twist-shaped tri-probe heterojunction device would be formed,which reserves the carbon edge channel.According to density functional theory(DFT)and non-equilibrium Green’s function(NEGF)calculation method,the electron transport properties of the tri-probe device are investigated.The results indicate that one kind of spin electron can transit from one electrode to the other via the single side channel of the heterojunction in both ferromagnetic(FM)and antiferromagnetic(AFM)states,achieving 100%spin-polarized electron transport.When the gate voltage is applied to the central region,the current decreases with the increase of the gate voltage.When the gate voltage is greater than 0.5 V,the electron transport channel is completely blocked and both spin electrons cannot pass through the tri-probe device,indicating that the electron transport capacity of the device can be regulated by the gate voltage.Furthermore,if the device is deformed by external force,the electron transport capacity is almost unchanged as long as the shape variable is less than 6.7%.The findings provide a strong theoretical basis for the design of pure spin current devices based on silicon carbide nanoribbons.