Molecules used to shrink flash memory

molecules used for flash memory
Conventional flash drives. Image by Rico Shen.

Thanks to Michael Oberlin for pointing out some technical errors I had in this article. They have now been corrected.

Scientists have used molecules to shrink the size of flash memory drives.

Flash memory is the technology behind the portable computer memory drives known as USB sticks or pen drives. Flash memory has no moving parts so the info stored on flash drives is stable even when moved or exposed to different temperatures. 

Flash memory works by electrically writing and erasing information. Each flash drive has a memory chip comprising many tiny memory cells. When the electrical charge in each memory cell is altered, information is encoded as either hi or lo bits. Conventional flash memory can read and write megabytes of data each second. And even though pen drives are already conveniently small, much more data could be stored on them if it were possible to make the individual memory cells smaller.

Using current technology, each memory cell is at least ten nanometres in size. Scientists have tried in the past to use various molecules to make smaller flash drives but most non-metallic molecules do not conduct electricity well and are not stable across a wide range of temperatures. Flash memory processing produces high temperatures, so components must be temperature resistant to work. However, this year a team of scientists from Scotland and Spain discovered that two selenium oxide molecules inside a cage of titanium oxide could work as functional flash memory. For chemists, the molecular formula they used was n[W18O54(SeO3)2]4-. The cage and molecules are only one nanometre across. These molecules worked the same as conventional flash memory by storing charges to encode bits of information. Storage was stable up to 336 hours, which was as long as the scientists tested.

The molecular based flash memory, while much smaller than conventional flash memory, requires high voltage to write or delete information and is much slower than conventional flash drives. It takes 0.1 second to program or erase the molecular flash memory and 100 microseconds to read.

This is the closest scientists have come to developing a molecular based flash memory drive. The scientists involved believe they can tweak their set up to make it faster and stable over a longer time period.

The Scientific Paper:

Busche et al. Design and fabrication of memory devices based on nanoscale polyoxometalate clusters. Nature. 2014.

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