South Korean researchers have used graphene quantum dots instead of nanocrystals as the discrete charge trap material for storing data in commercial flash memories.
The researchers, Soong Sin Joo, et al., at Kyung Hee University and Samsung Electronics, based in Yongin, South Korea, published their findings in a paper on graphene quantum dot flash memories in a recent issue of Nanotechnology.
Data is usually stored as electric charge in polysilicon layers in today's commercial flash memories. As polysilicon is a single continuous material, defects in the material can interfere with the desired charge movement, which can limit data retention and density, reports Phys.org.
The researchers were focusing on solving this problem by storing charge in discrete charge traps, such as nanocrystals, which prevent unwanted charge movement because of its lower sensitivity to local defects.
Now they have gone ahead and used graphene, which is already popular as an attractive material for next-generation electronics and photonics.
Graphene quantum dots of three different sizes (6, 12, and 27 nm diameters) were incorporated between silicon dioxide layers to test the trapping of charge material. It was found that the memory properties of the dots differ depending on their sizes.
While talking to Phys.org, Suk-Ho Choi at Kyung Hee University said this is the first successful application of graphene quantum dots in practical devices, including electronic and optical devices.
"This is the first report of charge-trap flash nonvolatile memories made by employing structurally characterized graphene quantum dots, even though their nonvolatile memory properties are currently below the commercial standard," Ho Choi added.
Graphene quantum dot memories have shown potential, with an electron density comparable to that of memory devices based on semiconductor and metal nanocrystals.
Future improvements to the devices are further expected to enhance performance and discovery of new applications, say the researchers.
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