Nano-physics of transient phenomenon in semiconducting devices and circuits

Abstract

As devices are scaled down to nanoscale, the high-field and quantum effects are becoming important in characterization and performance evaluation of semiconducting devices and circuits. By using the theory developed by Arora [1], transient phenomena in semiconducting devices and circuits is elaborated. It is shown that in the high-electric field, the current is limited by the saturation velocity that is ballistic, independent of scattering interactions. The enhanced scattering in quantum wells reduces the mobility of a given device, but does not change the nature of saturation velocity. The saturation velocity is comparable to thermal velocity for non-degenerate semiconductors and Fermi velocity for the degenerate semiconductors. The emission of an optical phonon may further lower this velocity. Similarly, transit-time delay and RC switching delays are enhanced over and above what is expected for the application of Ohm’s law. The effect of current and voltage division laws is also elaborated.