Flash memory breaches nanoscales

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In what is considered a breakthrough in computing hardware, a team of scientists from Glasgow has proposed a way to harvest molecules and construct nano-sized non-volatile (permanent) storage devices, also known as flash memory devices. In a letter published in Nature today (November 20), Christoph Busche of WestCHEM School of Chemistry, University of Glasgow, and 12 others have written about their efforts to engineer molecular flash memory using nanoscale polyoxometalate clusters instead of the conventional metal-oxide semiconductor (MOS) devices.

The challenge

It is a great challenge to reduce the size of conventional MOS flash memories to sizes below ten nanometres. This poses a problem when one tries to build small flash memory devices. Hence other options have been pursued for quite some time, including those using proteins and other molecules. However, using these molecular memories involved integrating them with the MOS technologies, which was proving to be difficult and several candidates had been tried and found wanting in this attempt. The Glasgow group, headed by Leroy Cronin, has found a suitable candidate in the polyxometalate molecules.

When such a molecule is doped with the selenium derivative [(Se(IV)O3)2]2- a new type of oxidisation state (5+) is observed for the selenium. This new oxidation state can be observed at the device level, and this can be used as a memory.

Device simulation

The authors demonstrate this using a device simulation. Their work suggests a route to building molecular flash memory devices.

Flash memory is in everyday usage now. It is used in digital cameras, USBs and various other places. Unlike a computer’s RAM, which is volatile — meaning that the memory stored in it will dissipate once power supply is broken — a flash memory can retain what is written on it even when power supply is discontinued. For that reason it is called a non-volatile memory. So long, flash memories have been constituted using MOS technologies. This paper now suggests a new way of going beyond its nanoscale limitations.

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