Ballistic calculation of nonequilibrium Green's function in nanoscale devices using finite element method
Ballistic calculation of nonequilibrium Green's function in nanoscale devices using finite element method
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DOI：
10.1088/0022-3727/42/10/105109
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发表时间：
2009-05
期刊：
影响因子：
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通讯作者：
O. Kurniawan;P. Bai;E. Li
中科院分区：
文献类型：
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作者：
O. Kurniawan;P. Bai;E. Li
为了研究二维纳米器件，给出了一个全量子力学系统的弹道计算。模拟采用了非平衡格林函数(NEGF)方法来计算器件的输运特性。虽然大多数可用的软件使用有限差分离散技术，但我们的工作选择使用有限元方法来表示NEGF计算。在弹道装置的计算中，有限元方法具有一定的优势。在有限元分析中，弹道装置的浮动边界条件自然得到满足。本文给出了一种适用于沟道长度为10 nm、体厚为3 nm的双栅MOSFET器件的NEGF计算的详细有限元公式。研究了器件的势能、电子密度、横向能量积分的费米函数、局域态密度和传输系数。我们发现，传输系数受到源和沟道之间势垒顶部的显著影响，而势垒的顶部又取决于栅极控制。这支持了这样一种说法，即弹道装置可以通过屏障顶部的传输特性来建模。因此，本文给出的全量子力学计算证实了纳米器件中的弹道输运理论。
A ballistic calculation of a full quantum mechanical system is presented to study 2D nanoscale devices. The simulation uses the nonequilibrium Green's function (NEGF) approach to calculate the transport properties of the devices. While most available software uses the finite difference discretization technique, our work opts to formulate the NEGF calculation using the finite element method (FEM). In calculating a ballistic device, the FEM gives some advantages. In the FEM, the floating boundary condition for ballistic devices is satisfied naturally. This paper gives a detailed finite element formulation of the NEGF calculation applied to a double-gate MOSFET device with a channel length of 10 nm and a body thickness of 3 nm. The potential, electron density, Fermi functions integrated over the transverse energy, local density of states and the transmission coefficient of the device have been studied. We found that the transmission coefficient is significantly affected by the top of the barrier between the source and the channel, which in turn depends on the gate control. This supports the claim that ballistic devices can be modelled by the transport properties at the top of the barrier. Hence, the full quantum mechanical calculation presented here confirms the theory of ballistic transport in nanoscale devices.