A view of nanoscale electronic devices

Recent evolutionary and revolutionary developments in electronic devices are discussed. Three terminal electronic devices have made tremendous strides to the point of outperforming predictions made only a only a few years prior. All this is credit to the fine fabrication technologies and device deigns developed. A case in point is the MOSFET with gate dimension of mass-produced devices projected to be less than 13 run by the year 2013 with some 60 billion or more transistors per chip. With new lithographic tools, he clock frequency of CPUs will be boosted to 10 GHz in 200506, possibly earlier, with THz frequency performance at the device level. This was made possible primarily by employing simple scaling rules and device design modifications. Further developments and some tolerance to tunneling currents will most likely scale the silicon FETs down to approximately 3 run gate lengths, although below about 10 nm the devices would be extremely sensitive to random fabrication fluctuations, and their power consumption would grow very significantly. So far no other electron device, comparable with the FET in functional universality, has been found for sub-3-nm operation. For example, single-electron transistors, which are scalable to atomic size, suffer from low voltage gain and high sensitivity to single charged impurities. However, there are some exciting prospects of using hybrid SET/FET circuits in new architectures for advanced information processing, and several promising ideas for terabit memories and electrostatic data storage. What fueled the mind-boggling speed with which electronic devices have been scaled down seems to be also providing the impetus to explore self-forming modes of reduced dimensional structures. Among them are the various tubular forms of carbon, dubbed the "carbon nanotubes" with diameters under 20 nm. Carbon nanotubes could be made conducting or semiconducting thereby forming the basis for one-dimensional devices or beyond. Switches and simple circuits based on carbon nanotubes have already been demonstrated. With similar goals, researchers began to engineer organic molecules so that their physical and electronic properties could be tailored for electronic function also. Molecules are synthesized using an approach that builds nano structures at the atomic, molecular, or single device level. Though abyssal, transistor operation has been demonstrated (molecular transistors will not be discussed due to space limitations). In this article, scaling of MOSFETs with new device designs to combat the deleterious short channel effects followed by a short discussion of single electron transistors and carbon nanotube based device structures will be presented.