Nanoelectronics- Nanotechnology in electronics

The quest to find a worthy successor for the C-MOS has emerged out to what is known as nanoelectronics. Many research groups, universities, organizations (like DARPA)and companies like intel and IBM are engaged in developing a technology that is compact enough to make the chips even smaller without compromising with the cost and power efficiency. The Moore’s law which is now a standard for development pace in the electronics industry states that in every 18 months the number of transistors will double on a chip, but as we have reached the limit of resizing the MOSFET; what’s required is a new technology that can be implemented on a chip for ensuring continuous pace in the processor speeds.

 Broadly speaking nanoelectronics may refer to as many as dozens of these approaches to replace the existing MOSFET technology plus the other applications of nanotechnology in advancing the present electronic devices.

 From foldable paper transistors to the use of 2-D graphene and graphene based materials or simply replacing the electrons from photons (photonics), nanoelectronics ranges far and wide. Thus the aim of nanoelectronics is a major breakthrough, and though it is very obvious that it will take time to experience its presence in the market; the on-going research and the ever changing nature of technology ensures a revolution to come.

Although transistors these days have sizes in the range of 22-28 nanometers (a nanometer is 10^-9 of a meter) they still aren’t covered in nanotechnology because unless the quantum mechanical aspects came into being they can be simply governed by the classical laws of physics, But in nanoelectronics the sizes are so small that the quantum mechanical aspects are also be taken into consideration. This may pose a difficulty in understanding their motion and flow.

Here are few approaches or applications of nanoelectronics. No one can say which one of them will be the technology of future although some of them have better prospects than others, but most of them are in development phase:

1.      Graphene

         One of the most likely successors to the MOSFET, as the research projects are far into their final phases and companies like IBM have already made their successful prototypes. IBM actually developed a graphene based processor that can execute on 100GHz speed. It is widely accepted that graphene based chips will hit the markets in the next decade. Graphene which has entirely different properties from any known material when used in chips in place of silicon provides the electrons a medium that enables them to move with light like velocities, much faster than what they are capable of achieving in doped silicon chips. Graphene has a honey-comb like structure but it is much thinner than graphite (in fact only a few atoms thick). It shows properties that are entirely different from other materials. It is neither a metal nor a semiconductor and obviously not an insulator too, therefore some of the researchers call it a semimetal, and when you roll it up you get a carbon nanotube which has its very own applications. One more interesting use of graphene is to develop flexible gadgets which are built using graphene ink.

Despite giving electrons light like properties we could also have used photons, which bring us to this next approach.

2.      Silicon Photonics

As already discussed in this blog silicon photonics also claims to be a natural successor of MOSFETs. The idea is to use photons in place of electrons which will reduce considerably the signal degradation effect of metals like copper and provides high speed data transfer with the speed of light. Intel has already developed a link using photonics which is capable of transferring at the rate of 50 Gbps. Yeah right! 50 Gigabytes per second – a speed powerful enough to transfer about 25 movies a second, but sadly it was just a test vehicle and implementing it requires to convert the entire computer set-up from electronic device to all-optical device, because optoelectronic interfaces makes the device run even slower. However a research to develop nanofibers might bring hope to this approach which is quite well accomplished when Penn University researchers developed a NAND gate from the cadmium sulfide nanowires but making the entire circuitry from it is still a mammoth task. Thus in matter of practical possibilities graphene is ahead of photonics.

3.       Molecular scale electronics as a replacement to FPGAs

FPGA refers to Field Programmable Gate Array. They are integrated circuits that are configurable according to the application. Molecular scale transistors have self assembling properties that can be used as a replacement to FPGAs. The molecular scale electronics follows a ‘Bottom-up’ approach in nanotechnology where transistors are made using molecules in say a chemistry lab. These are than multiplied at a very high rate. This is in contrast with top-down approaches such as lithography where bulky materials are used to make smaller scale transistors. This technology is in fact the limit of miniaturization; however it is still far from being practically utilized.

4.      Transistors using carbon nanotubes (CNTFETs)

Carbon nanotubes are considered an even better alternative than graphene which has many desirable electrical properties on its own. CNTFETs (Carbon NanoTube Field Effect Transistors) are now being used for making compact FETs. IBM has successfully created a logic circuit using 10000 CNTFETs at a density of one billion CNTFETs per square centimeter. This in-fact performed five times better than silicon FETs. It is estimated that over a period of seven years this technology will be ready to be implemented on chips. They use single carbon nanotube or an array of them as a replacement for bulky channel material in FETs.

5.      Display using Quantum dots

Quantum dots are semiconducting nanocrystals, which can be used as a display technology where light is emitted on demand just like in OLEDs, thus reducing considerable amount of power consumption. This property makes them useful as an enhancement to the LCD screens used in TVs computers, mobile phones and other flat-panel displays. They are seen as a substitute to OLEDs (Organic Light Emitting Diodes). They edge over OLEDs because of their comparatively very low cost of manufacturing. Moreover unlike OLEDs they can be used in non- planar and flexible displays also.

The list of nanoelectronic approaches is in fact seems to be endless because of the extensive research in this area; therefore this list is no way complete in any respect. Molybdenum Sulphide 2-D material, magnetoelectric random access memory, nanowires using iron and nickel alloys to create high density memory devices are a just a few other approaches which are also a part of this ‘nanoelectronics’ initiative.