HSPICE implementation of a numerically efficient model of CNT transistor

This paper presents the algorithms of an implementation of a numerically efficient carbon nanotube transistor (CNT) model in HSPICE. The model is derived from cubic spline non-linear approximation of the non-equilibrium mobile charge density. The spline algorithm exploits a rapid and accurate solution of the numerical relationship between the charge density and the self-consistent voltage, which results in the acceleration of deriving the current through the channel without losing much accuracy. The output I-V characteristics of the proposed model have been compared with those of a recent HSPICE implementation of the Stanford CNT model and published experimental I-V curves. The results show superior accuracy of the proposed model while maintaining similar CPU time performance. Two versions of the HSPICE macromodel implementation have been developed and validated, one to reflect ballistic transport only and another with non-ballistic effects. To further validate the model a complementary logic inverter has also been implemented using the proposed technique and simulated in HSPICE.