I. Introduction
The pursuit of moore's law, as predicted by the International Technology Roadmap for Semiconductors (ITRS) has pointed to significant future intrinsic device hurdles (such as leakage, interconnect, power, quantum effects) to the capability of realizing system architectures using CMOS transistors with the performance levels required by future applications. It is recognized that these limitations, as much fundamental as economic, require the semiconductor industry to explore the use of novel materials and devices able to complement or even replace the CMOS transistor in systems on chip within the next decade and before silicon based technology will reach its limits in 2020 when the channel length of MOSFET is below 10 nm.