Fully 3D quantum transport simulation
Fully quantum mechanical modeling is essential for a good prediction of device characteristics in ultra-scaled nano devices. Ballistic nature of transport is becoming prominent in these devices (see e.g. G. Timp et. al., IEDM Tech. Dig., pp. 55-58 (1999), M. M. Chowdhury et. al., IEEE Trans. El. Dev. 54, pp. 1125-1131 (2007), etc.). At the same time, the most promising novel ultra-scaled devices (FinFETs, Tri-gate FET, etc.), in which quantum effects such as quantization and direct tunneling through gate oxide are very significant, are inherently two-dimensional (2D) or three-dimensional (3D), and one must solve the 2D or 3D quantum transport problem. The majority of fully quantum-mechanical transport solvers are 1D or 2D, and only a few solvers are truly 3D.
At ASU, we have developed a fully 3D self-consistent quantum mechanical simulator based on the efficient CBR method. At the present stage, the main goal of our research is to answer questions:
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When a fully 3D transport simulation is essential for nano-device modeling?
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What new effects does 3D modeling reveal?
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Can a fully 3D quantum transport simulation of realistic devices be performed within a reasonable frame of time?
3D electron density of the Tri-gate FET in on-state for tSi=4nm, h=5nm
In the considered device both side and top gates have tox=1.5 nm. For this Tri-gate device influence of the top gate is crucial not just for the electrostatics (capacitance), but for the gate leakage and drain current. Thus, the fully 3D quantum transport modeling is essential for Tri-gate FETs.
Dependency
of drain current per height on height (h).
2D current value (i.e. when h>>Lg=10 nm) is taken as a reference.
In the absence of interface roughness (e.g. with ideal
interfaces), the drain current per unit height is increasing
with decreasing the height. Quantum confinement is stronger for
narrower devices, which leads to higher electron density in the
middle of the channel, which results in higher current densities.