New recipe for memory devices
doi:10.1038/nindia.2012.64 Published online 30 April 2012
Researchers have designed a new kind of memory device using multi-walled carbon nanotubes (MWCNTs) and ferroelectric oxides. This device will come handy in making new generation memory devices with reduced current leakage.
Despite their use in memory devices, ferroelectric materials fail to meet the rapidly decreasing size requirements of silicon circuitry. In addition, such materials have drawbacks like large current leakage and insufficient switchable charge with reduced mechanical strength. Recent research has shown that a combination of ferroelectric materials and carbon nanotubes may help overcome these drawbacks.
To fabricate memory devices with better electrical and mechanical properties, the researchers combined MWCNTs with lead-containing ferroelectric oxide. They grew MWCNTs on silicon substrates using plasma-enhanced chemical vapour deposition (PECVD) technique. They laid the ferroelectric materials on the tip of MWCNTs using pulsed-laser deposition (PLD) technique.
Sophisticated imaging techniques revealed the shape of the device like ferroelectric materials-coated forest-like MWCNTs with diameters between 100 and 150 nm. Images showed clear hybrid structure with nanotube having 80 nm diameter covered by a 50-80 nm ferroelectric layer.
The memory device exhibited high switchable charges at room temperature. It was also compatible with silicon, could hold charge for a long time and was fatigue-free. "It can be used as a non-volatile memory element for future ferroelectric random access memory and would be useful for nano-electromechanical system applications," says Ashok Kumar, one of the researchers.
The authors of this work are from: National Physical Laboratory, New Delhi, India, Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, and Department of Physics and Astronomy, University of Nebraska, Lincoln, USA, Electrical Engineering Division, Department of Engineering and Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK.