Prediction of a two-transistor vertical QNOT gate

Abstract

A new design of quaternary inverter (QNOT gate) is proposed by means of finite-element simulation. Traditionally, increasing the number of data levels in digital logic circuits was achieved by increasing the number of transistors. Our QNOT gate consists of only two transistors, resembling the binary complementary metal-oxide-semiconductor (CMOS) inverter, yet the two additional levels are generated by controlling the charge-injection barrier and electrode overlap. Furthermore, these two transistors are stacked vertically, meaning that the entire footprint only consumes the area of one single transistor. We explore several key geometrical and material parameters in a series of simulations to show how to systematically modulate and optimize the quaternary logic behaviors.