Future of Computation with Electronic Nanotechnogy Presented By Shubhra Karmakar

Spring 2004 CS-603 Nanotechnology 2 Outline  Technology shifts in computation  What is electronic nanotechnology?  Approaches to nanoelectronic devices  Nanoelectronic devices in future computers  Solid-state nanoelectronic devices  Molecular electronic devices  Conclusions

Spring 2004 CS-603 Nanotechnology 3 Technology Shifts in Computation  Rapid increase in transistor density i.e., number of transistors/chip  This Increase being dictated primarily by - Need for greater computational speed - Need for greater computational memory  Increase in transistor density  Scaling down device sizes - Size shift: Inches to Microns to Nanometers - Technology shift: Micron technology to Nanotechnology

Spring 2004 CS-603 Nanotechnology 4 What is Electronic Nanotechnology ?  Electronic Nanotechnology  Nanoelectronics  Nanoelectronics: Development of electronic devices having smallest feature size between 1 to 10 nm  Possible electronic devices in computers that can be scaled down to nano levels - CMOS - Memory - Switches

Spring 2004 CS-603 Nanotechnology 5 Place of Nanoelectronics in Moore’s Space 1.E+11 CMOS Doubles every 1.0 year Transistors Doubled every 2.3 year 1.E+10 1.E+09 1.E+06 1.E+03 1.E+00 1.E-03 1.E-06 Mechanical Relays Doubled every 7.5 years Nanometer doubles every few months? From Gray Turing Award Lecture Ops/sec

Spring 2004 CS-603 Nanotechnology 6 Approaches To Nanoelectronic Devices  Two approaches: - Develop “nano” descendants of present solid-state microelectronics - Fabricate nano devices from molecules  Molecular electronics approach Path I Scaling down current S-State devices Path II Molecular Electronics

Spring 2004 CS-603 Nanotechnology 7 Promising Nanoelectronic Devices in Future Computers  Path I: Nanoelectronic Solid-State Devices - Nano CMOS - Resonant Tunneling Diode (RTD) - Single Electron Transistor (SET)  Path II: Molecular Electronic Devices - Molecular Electronic RTD - Spintronics Quantum-Effect Devices

Spring 2004 CS-603 Nanotechnology 8 The Future of CMOS  Current VLSI systems rely heavily on CMOS technology  With nano miniaturization: - A CMOS is predicted to have transistors by Operating speeds will be 10 – 15 GHz (compare to current 1 GHz !)  Example: Today’s CMOS gate length = 120 nm  22 nm (2014) 100 nm

Spring 2004 CS-603 Nanotechnology 9 Scaling Limits of CMOS  As we scale down, devices will become - More variable - More faulty  As we scale down, fabrication will become - More expensive - More constrained  As we scale down, design will become - More complicated - More expensive From Shibayama et al, 1997

Spring 2004 CS-603 Nanotechnology 10 Resonant Tunneling Diode (RTD)  Made by placing insulating barriers on a semiconductor => creates island or potential well between them  Only finite number of discrete energy levels are permitted in the island  Electrons can pass through the island by quantum tunneling - If incoming electron energy matches (or resonates) with an energy state inside the island, then current flows through: “ON” state - If energy states inside and outside do not match: “OFF” state  Multiple logic states are possible - As voltage bias is increased and resonant states are established, switches “ON. Then switches “OFF” and then switches “ON” as soon as next level energy states match

Spring 2004 CS-603 Nanotechnology 11 Single Electron Transistor (SET)  Bell Lab researchers fabricated the first SET in 1987  Similar tunneling concept as RTDs - One electron tunnels from source to drain, through the barriers

Spring 2004 CS-603 Nanotechnology 12 Summary of Quantum-State Nanoelectronic Devices DeviceAdvantagesDisadvantagesStatus RTD - Multiple logic states - Semiconductor based - Capable of large scale fabrication - Same scaling limitations as CMOS - In production SET - High Gain - Similar operation to FET - Very low temperature - Control challenges - Experimental

Spring 2004 CS-603 Nanotechnology 13 Molecular Electronic Devices for Future Computers  Molecular Electronics – Uses covalently bonded molecules to act as wires and switching devices - Molecules are natural nanometer-scale structures E.g., A molecular switching device is only 1.5 nm wide!  Molecular electronics will bring the ultimate revolution in computing power - 1 trillion switching devices on a single CPU chip! - Terabyte level memory capacities!  Primary advantage – can be synthesized in large numbers; in the order of Avagadro’s number (10 23 )  Present day challenge is to develop methods to incorporate these devices in circuits

Spring 2004 CS-603 Nanotechnology 14 Molecular Electronic Devices (…continued)  Molecular Electronic Resonant Tunneling Diode - Concept is similar to solid-state RTD  Chains of Benzene ring act like conductive wires - “CH 2 ” (Methylene group) act as electron barriers - Island or potential well formed between them  Potential well in molecular RTDs is 10 to 100 times less than solid-state RTDs

Spring 2004 CS-603 Nanotechnology 15 Molecular Electronic Devices (…continued)  Spintronics - Spintronics  Spin electronics  Magneto-electronics - Discovered in 1988 by German and French physicists; IBM commercialized the concept in Exploits the “spin” of electrons, rather than “charge” in information circuits - Information is stored into spins as a particular spin orientation (up or down) - Spins, being attached to mobile electrons, carry the information along a wire  Spin orientation of electrons survive for a relatively longer time, which makes Spintronic devices attractive for memory storage devices in computers

Spring 2004 CS-603 Nanotechnology 16 Spintronics (…continued) Computers Hard Drive - Uses magnetic spin to store long- term information - Information is retained on power loss RAM & CPU - Uses charge to store information - Information is lost on power loss Magnetic disk drives--like this 1 GB IBM Microdrive, are the most common devices that takes advantage of Spintronics

Spring 2004 CS-603 Nanotechnology 17 Spintronics (…continued)  Advantages of Spintronics-based computers - Non-volatile: no loss of data during a power loss - Compact: because of increased miniaturization - Energy efficient - Highly customizable: Reprogrammable CPU  Magnetic RAM is a more imminent development than a magnetic CPU (CPU involves more complex h/w)

Spring 2004 CS-603 Nanotechnology 18 Spintronics (…continued) Potential Market for Nanoelectronic Memory and Logic Products, Adapted from: BCC Research Report

Spring 2004 CS-603 Nanotechnology 19 Snapshot of Active Research in Nano Devices Nano CMOS RTDsSETsMolecular Devices MRAMHard Drive

Spring 2004 CS-603 Nanotechnology 20 Conclusions  The strides being made in nanoelectronics promise an exciting future for computation  Despite enormous progress in demonstration of nanoelectronic devices, many challenges remain - Solid-state nanoelectronic devices: Important challenges are that of fabrication, reliability and design - Molecular electronic devices: Challenge is to incorporate these devices in circuits  Spintronics device development and commercialization of this technology in memory devices of computers seems to hold tremendous potential "Don't worry about what anybody else is going to do… The best way to predict the future is to invent it. Really smart people with reasonable funding can do just about anything that doesn't violate too many of Newton's Laws!" — Alan Kay in 1971

Spring 2004 CS-603 Nanotechnology 21 References        

Spring 2004 CS-603 Nanotechnology 22 Questions?