Glass tops the class

A potentially fast switching glass has won the 2005 Westminster Medal for a PhD student from Southampton University. Rob Simpson scooped the £1,000 prize money in a poster competition held at the House of Commons on 14 March, organised by SET for Britain, an organisation aimed at promoting Britain’s top younger researchers in science, engineering and technology.

Simpson’s project came top out of the 170 that were accepted. ‘I didn’t see the day as a competition,’ says Simpson, ‘I attended for the experience and opportunities which sometimes arise at such events. I was completely shocked, but obviously delighted when my name was called out as the winner.’

Simpson’s winning project is based on the application of novel glasses, more specifically chalcogenide materials for electrical and optical phase change data storage technologies. The active layer of rewritable CDs and DVDs is formed from this material.

Chalcogenides are compounds that contain at least one of the chalcogens, or Group 16 elements of oxygen, polonium, sulphur, selenium and tellurium. ‘Some chalcogenide materials are known to be stable in both their amorphous and crystalline states,’ continues Simpson. By changing these materials between these states, they can be used as switching devices.

The breakthrough for Simpson and his colleagues at the Optoelectronics Research Centre (ORC) in Southampton, UK, came when they were searching for new phase change materials. ‘We have found a completely new phase change chalcogenide material which we hypothesise will be fast switching. This material can be readily doped with a number of elements to improve its phase change properties,’ says Simpson.

The ORC is at the forefront of developing phase change memories. In outlining the advantages of phase change memory, Simpson says they are non-volatile, have superior write cycle endurance over Flash technology – meaning that bits of data can be written in tens of nanoseconds – and they are also radiation insensitive.

Simpson’s work builds on that of Stan Ovshinsky, a pioneer of chalcogenides research in the USA who first demonstrated the switching nature of these materials.

Text courtesy of Materials World News April 2005.