Optical memory using leaky ferroelectrics?

A schematic of the bismuth ferroite spatially-resolved photodetector showing the diffraction-limited laser raster-scanning the device channel. The inset is a photograph of the device electrodes taken through an optical microscope.

Ferroelectrics have already found applications in non-volatile random access memory (RAM) and so far the Fujitsu company has made more than 1 billion FeRAM devices (if you open up a Playstation 2, for example, you’ll find one inside).  One critical, yet often overlooked, problem with ferroelectrics is leakage in which the material has a measurable dc conductivity.  Leakage is tolerated to a certain extent depending on the intended application and it can be limited by careful processing and doping.

However, leaky ferroelectrics, and ferroelectrics in general also exhibit complex – sometimes mysterious – optoelectric characteristics that have been observed for 50 years but are still not fully understood.  Taking advantage of this mysterious behaviour, a collaboration between scientists at POSTECH and KAIST in Korea, Rutgers University and the University of Cambridge has probed the optoelectric behaviour of bismuth ferrite (BiFeO3) at the nanoscale and proposed a novel optical memory application.

They report in Advanced Optical Materials a BiFeO3 photodetector, in which a chopped laser beam scans the surface of a BiFeO3 film with a spot size of ~ 500 nm.  Using this technique it is possible to measure both the photocurrent and photovoltage spatially, initial results that bode well for memory applications.

PDFLink to the original paper on Wiley Online Library
About Tim Adams

Tim is the editor of Steel Research International and editor-in-chief of Advanced Engineering Materials. You can follow him on Google+.

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