Researchers at the Zernike Institute of Advanced Materials at the University of Groningen have developed a technology for a plastic ferro-electric diode which they believe will achieve a breakthrough in the development of ultra low-cost plastic memory material. Their findings will be published in the July edition of Nature Materials, a publication of the leading scientific journal Nature.
The newly developed technology is similar to that used in Flash memory chips. In both cases, the memory retains data without being connected to a power source. Flash memory chips are used in memory sticks, MP3 players, cellular phones and in the memory cards of digital cameras. The researchers at the Zernike Institute of Advanced Materials expect the new technology to lead to the development of comparable products possibly even more significant. One product they have in mind is an electronic price tag which could be read radiographically at the cash desk of retail stores, replacing the bar codes currently in use. Another possible application is for the material to be used in packaging material which could warn consumers when a product is nearing its expiration date.
In 2005, a joint team of researchers from the University of Groningen and Philips already successfully integrated a ferro-electric polymer into a plastic transistor. Because the ferro-electric material can be switched between two different stable states through the use of a voltage pulse, it operates as a ‘non-volatile’ memory (meaning that the material retains data without being connected to a power source). The disadvantage of such a transistor is that three connections are needed for programming and reading out the memory, complicating the fabrication. The challenge was therefore to realize comparable functionality within a memory component carrying only two connections: a diode.
The breakthrough was accomplished during the research project of PhD student Kamal Asadi, which was financed by the University of Groningen. It is based on a radically new concept: instead of stacking a layer of semiconducting material on a layer of ferro-electric material, a mixture of these two materials is used. The ferro-electric characteristic of the mixture is then used to direct current through the semi-conducting part of the mixture.
The new memory diode can be programmed quickly, retains data for a long time and operates at room temperature. The voltages needed for programming are low enough for the diode to be used in commercial applications and the material can be manufactured at low cost using large-scale industrial production techniques. The University of Groningen has obtained a patent on the new material.