The quantum capacitance limit of high-speed, low-power InSb nanowire field effect transistors

The performance metrics of InSb nanowire (NW) FETs are investigated using an analytical 2-band model and a seminumerical ballistic transport model. The first analysis of the diameter dependence of the current, gate delay, power-delay product, and energy-delay product of InSb NW FETs, which operate in the quantum capacitance limit (QCL), are presented. Because of their small density of states, relatively large diameter, ≤ 60 nm, InSb NW FETs operate in the QCL. Both the energy-delay and power-delay products are reduced as the diameter is reduced, and optimum designs are obtained for diameters in the range of 10 - 40 nm. Power-delay product varies from 2× 10
^-20
J to 68× 10
^-20
J for all devices with a source Fermi level range of 0.1 - 0.2 eV. The gate delay time for all devices varies from 4 - 16 fs and decreases as the NW diameter increases. These NW FETs provide both ultra-low power switching and high-speed.