Home > Press > Good Memory
On the way to plastic electronics: polymer-based dynamic random access memory (DRAM)
Posted on April 14, 2006
Smaller, lighter, more compact devices that can do more and more, work faster, and juggle more data—these demands are pushing conventional semiconductor technology up against its limits. In the future, plastics will have to take over. A number of polymeric electronic components have already been made. Researchers at the National University of Singapore and the Institute of Microelectronics in Singapore have now successfully produced DRAM storage based on a plastic.
The Singaporean team also recently made flash memory (a rewritable memory) and write-once read-many-times (WORM) memory based on polymers. Now they have introduced another type of memory, dynamic random access memory (DRAM), based on a polymer. In this “short-term” or “dynamic” memory, electronic devices temporarily store all processes—storage units are updated by refreshing voltage pulses.
In contrast to a semiconductor chip, which “keeps track” of data in the form of electrical charge, the “0” and “1” signals in polymer-based memory are stored as high and low conductivity, respectively. The researchers produced a special copolymer, a plastic whose long molecular chains are made of two different components that are finely tuned to each other. This polymer is embedded as a thin film between two electrodes. The polymer is initially in the OFF state, which is characterized by low conductivity. A barrier hinders the flow of electrons through the film. In order to “write” to the memory, a low voltage above a certain threshold (-2.8 V) is enough to switch the copolymer into a highly conducting state, the ON state. The memory is “read” by means of voltage pulses below the threshold. The secret behind this device is the combination of the barrier and a kind of “pit trap” for charge carriers. If the barrier is first overcome above the threshold, the pits are filled with charge carriers. The altered electrical field then causes the barrier to become ineffective. The current can then flow through the film unhindered. The pits are “shallow”, which allows the charge carriers to come out easily: If no voltage is applied for over two minutes they “climb” out of the pits on their own and the memory “forgets” its programming and returns to the OFF state. This is just what it should do as “dynamic” memory. “Erasing” the memory is accomplished by an opposing voltage pulse above +3.5 V. This immediately returns the memory to the original OFF state with empty traps. Renewed application of more than -2.8 V always returns the memory to its writeable state.
Author: En-Tang Kang, National University of Singapore (Singapore), www.chee.nus.edu.sg/staff/kang.html
Title: A Dynamic Random Access Memory (DRAM) Based on a Conjugated Copolymer Containing Electron-Donor and -Acceptor Moieties
Angewandte Chemie International Edition
, 2006, 45
, No. 18, 2947–2951, doi: 10.1002/anie.200504365
or David Greenberg (US)
or Julia Lampam (UK)
Copyright © Angewandte Chemie
If you have a comment, please Contact
Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014
Can our computers continue to get smaller and more powerful? University of Michigan computer scientist reviews frontier technologies to determine fundamental limits of computer scaling August 13th, 2014
An Inkjet-Printed Field-Effect Transistor for Label-Free Biosensing August 11th, 2014
Rice's silicon oxide memories catch manufacturers' eye: Use of porous silicon oxide reduces forming voltage, improves manufacturability July 10th, 2014
Fonon Announces 3D Metal Sintering Technology: Emerging Additive Nano Powder Manufacturing Technology August 28th, 2014
SouthWest NanoTechnologies CEO Dave Arthur to Discuss “Carbon Nanotubes and Automotive Applications” at The Automotive Composites Conference and Expo 2014 (ACCE2014) August 28th, 2014
Nanodiamonds Are Forever: A UCSB professor’s research examines 13,000-year-old nanodiamonds from multiple locations across three continents August 27th, 2014
Competition for Graphene: Berkeley Lab Researchers Demonstrate Ultrafast Charge Transfer in New Family of 2D Semiconductors August 26th, 2014
Leading European communications companies and research organizations have launched an EU project developing the future 5th Generation cellular mobile networks August 28th, 2014
Ultra-Low Frequency Vibration Isolation Stabilizes Scanning Tunneling Microscopy at UCLA’s Nano-Research Group August 28th, 2014
Novel 'butterfly' molecule could build new sensors, photoenergy conversion devices August 28th, 2014
New technique uses fraction of measurements to efficiently find quantum wave functions August 28th, 2014