Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Nanocrystals formation for nonvolatile memory using PLD

Abstract:
A novel method based on PLD has been formulated to produce nanocrystals embedded in high-k dielectrics. Application as nonvolatile memories gives advantages in good memory window and long data retention.

Nanocrystals formation for nonvolatile memory using PLD

Singapore | Posted on January 30th, 2007

Research in the field of nanoelectronics has been increasing in the recent years. This is true in particular for nonvolatile memories which have low power consumption with high density. Nonvolatile memories found their applications predominantly in many portable devices such as mobile phones, PDAs, etc. These devices gain advantage in using nonvolatile memories by exploiting the low power consumption and high density. As compared to the conventional floating gate memory, a structure having nanocrystals embedded in the dielectrics has exhibited the high potential to produce a memory with low operating voltage, high endurance, fast write-erase speeds, and better immunity to soft errors. The memory operation of these devices has been associated with the charge exchange between the nanocrystals and the inversion layer. Moreover, the use of high-k dielectric in place of the conventional SiO2 has enabled flash memory to obtain significantly improved programming efficiency on top of better data retention.

A group from Nanyang Technological University (NTU), School of Materials Science and Engineering, led by Asst. Prof. Lee Pooi See, has successfully developed a novel method based on pulsed laser deposition (PLD) to fabricate the memory structure of nanocrystals embedded in dielectric. By far, they have been successful in fabricating germanium (Ge), silicon dioxides (SiO2), strontium titanate (SrTiO3), and LaAlO3 embedded on a high-k dielectric. High-k dielectric used is lanthanide oxides, as they are potential candidates for gate insulator due to their desirable characteristics such as large band gap, high relative dielectric constant and low leakage current. In particular, lutetia (Lu2O3) is used because, despite the moderately high dielectric constant (~12), it is predicted to be thermodynamically stable on silicon, and it has a good conduction-band offset (CBO) with silicon. Among the lanthanide oxides, lutetia has the highest lattice energy and the largest bandgap. Therefore, it was expected to show better hygroscopic immunity as well as lower leakage current than other lanthanide oxides thin films.

The method based on PLD process, was done by placing the target in an ultrahigh vacuum chamber and then ablating it with a KrF pulsed laser. The target to be laser ablated was first prepared from a high-purity (99.999%) round lutetia target and one small nanocrystals square plate wafer. The nanocrystals plate was glued using a chemically nonreactive adhesive onto the surface of lutetia target, making a two-layer assembly with only physical, but not chemical, contact between them. During the PLD process, the center of the target assembly was set to spin slowly about its central axis and the laser beam vaporized the two component materials alternately. The plume of the particles would then be deposited on the p-type (100) Si substrate which has had its native oxide removed. After the deposition, the thin film was subjected to post-deposition annealing.

Upon examination of the film structure under high-resolution transmission electron microscope (HRTEM), it could clearly be seen that the nanocrystals has been successfully synthesized. Resulting nanocrystals with diameter of around 7 nm and the area density of around 8 x 1011 cm-2, depending on the type of the nanocrystals, are observed in the planar TEM image. A trilayer nanocrystals memory capacitor structure was observed consists of an amorphous lutetia tunneling layer, nanocrystals and amorphous lutetia control layers.

All nanocrystals embedded samples show large memory effect caused by the charges stored in the nanocrystals and/or at the nanocrystals interfaces. The resulting C-t curve obtained experimentally showed very good charge retention characteristics. Using this proposed method, the size and the density of nanocrystals to be deposited could also be controlled by modification of the target.

####

About Nanyang Technological University, MSE
he School of Materials Science and Engineering offers engineering degree courses at the Bachelor, Master and PhD level. Research and development (R&D) carried out often goes hand-in-hand with the courses and programmes offered. Graduate students, academic staff and research staff all contribute to our R&D activities. Over the years, the School has set up state-of-the-art research facililties and infrastructure. Inter-disciplinary research is emphasized, involving faculty staff from other schools within NTU and overseas research institutions and universities.

For more information, please click here

Contacts:
Fatwa Firdaus Abdi
Phone: (65)98502420

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Chip Technology

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Dartmouth team creates new method to control quantum systems May 24th, 2016

Attosecond physics: A switch for light-wave electronics May 24th, 2016

Memory Technology

Hybrid nanoantennas -- next-generation platform for ultradense data recording April 28th, 2016

Magnetic vortices defy temperature fluctuations: Common magnetic mineral is reliable witness to Earth's history April 19th, 2016

A single-atom magnet breaks new ground for future data storage April 15th, 2016

Ames Laboratory physicists discover new material that may speed computing April 12th, 2016

Discoveries

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Finding a new formula for concrete: Researchers look to bones and shells as blueprints for stronger, more durable concrete May 26th, 2016

Announcements

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Deep Space Industries and SFL selected to provide satellites for HawkEye 360’s Pathfinder mission: The privately-funded space-based global wireless signal monitoring system will be developed by Deep Space Industries and UTIAS Space Flight Laboratory May 26th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic