Nanoelectronic Devices for the 21st Century

摘要

Both physical and economic considerations indicate that the scaling era of complementary metal oxide semiconductor will run out of steam around the year 2010. However, physical laws also indicate that it is possible to compute at a rate of a billion times the present speeds with the expenditure of only 1 watt ot electrical power. NASA has long-term goals for which ultrasmall semiconductor devices will be needed in critical applications: high-performance, low-power, compact computers for intelligent autonomous vehicles and petaflop (10(exp 15)) computing technology are two key examples. Ames Research Center has developed a Green's-function-based code to calculate the transport properties of carbon nanotubes (CNTs). The single most important promise of CNTs with regard to device application is their use as quantum wires. An important question is how disorder affects the conductance of these low-dimensional systems. To obtain an understanding of this, both the low-bias conductance, as a function of the gate voltage (Fermi energy) and the conductance as a function oi the applied bias in a CNT for two models of disorders, have been computed. These calculations show that in the presence ot weak uniform disorder, the low-bias conductance exhibits a dip as the Fermi energy is swept across the intersection of the first and second sub-bands.