Impact of oxide thickness on the performance of a GaAs NWFET

Euro-TMCS I: Theory, Modelling and Computational Methods for Semiconductors

物理学;计算机科学

Price, A.^1 ; Martinez, A.^1

College of Engineering, Swansea University, United Kingdom^1

关键词: Channel length;    Effective mass approximation;    Mode space approaches;    Non-equilibrium Green's function;    Oxide thickness;    Relative positions;    Strong confinement;    Tight binding;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/609/1/012004/pdf
DOI  :  10.1088/1742-6596/609/1/012004

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

Nanowire field effect transistors (NWFETs) are being considered as a replacement for planar MOSFETs at the end of the ITRS. In this work, the change in the relative position of the valleys due to the oxide thickness is investigated, and the subsequent effect this has on the drain current in each valley. An NWFET of cross-section 2.2×2.2 nm2and channel length 6 nm has been considered. The strong confinement at this scale can cause the low mass Γ-valley to become raised in energy, such that it is higher than the heavy mass L and X-valleys. This results in very low current in the device. It was found that increasing the oxide from 0.2 nm to 0.8 nm caused the Γ-valley to lower in energy, resulting in a higher current. Both ballistic and dissipative transport are considered. This was achieved through the use of the non-equilibrium Green's function (NEGF) formalism. The mode space approach in the effective mass approximation was deployed, and the conduction band masses were extracted from tight binding simulations. Scattering was found to cause a 65%, 44% and 36% in the current for a 0.2 nm, 0.8 nm and 1.6 nm oxide thickness respectively.