In this paper we have discussed the main challenges faced
by CMOS technology. The challenges are addressed from
different perspectives ; physical, material, power-thermal, technological, and economical. We have also presented alternative devices that are potentially able to overcome the limitation in
CMOS technology. At present, the research of these emerging
non-CMOS nanodevices is still in its infancy phase. Therefore,
researchers are urged to continue exploring and inventing
these new, high-performance, and cost-effective non-CMOS
nanodevices before the extinction of CMOS.