Memory effect in thin films of insulating polymer and C₆₀ nanocomposites

Abstract

We describe the use of C 60 fullerene molecules as the charge storage medium in an insulating poly-vinyl-phenol (PVP) polymer. The simple metal-organic-metal (MOM) sandwich structure devices deposited from solution exhibit distinct high and low conduction states, which can be used to program read, write and erase memory operations. The charge transfer and retention in C 60 molecules at room temperature has been confirmed by capacitance-voltage and Raman spectroscopy measurements. Conducting atomic force microscopy has been used to demonstrate that high and low conductance states persist even at the nanoscale.

Electrical bistability in a composite of polymer and barium titanate nanoparticles

“…In the off state, the typical measured current was of the order of 10 −6 A, while in the on state a typical current of 10 −5 A was measured, giving a measurable current difference between the two states. Memory retention time, as shown in figure 6, was also investigated, with the devices exhibiting a stable on/off current ratio for over 10 000 read cycles over a period of 5 h. The working mechanism of our MPM devices promises to be complex, and a number of mechanisms have already been proposed by various workers (Bozano et al 2004;Paul et al 2006;Paul 2007). At the same time, a broad qualitative understanding is possible.…”

“…In the case of molecular memory, a monolayer of molecules is deposited between metal electrodes (Reed et al 2001). In a polymer memory device, an admixture (a blend) of small organic molecules and/or metal nanoparticles in a polymer matrix is deposited between metal electrodes to form an array of memory elements (Paul et al 2006 Scott (2004) and Scott & Bozano (2007) highlighted several performance criteria that needed to be addressed before any new memory technologies would be capable of competing favourably with the current silicon technologies. Polymer memory devices may be able to fulfil the criteria highlighted in the aforementioned papers, and so far there have been demonstrations of devices based on metal nanocluster layers by Ma et al (2003), Bozano et al (2004) and Tondelier et al (2004).…”

Planar Non-Volatile Memory based on Metal Nanoparticles

“…These devices show dramatic changes of the electrical resistance, so-called resistive switching effect. Current-voltage characteristics switch reversibly between a low conductance off-state and a high conductance on-state [1][2][3][4][5][6][7]. This phenomenon has being intensively investigated worldwide for developing Resistive Random Access Memories (RRAMs), a possible competitor, and even replacement for flash memory and hard-disk drives.…”

Tristable electrical conductivity switching in a polyfluorene–diphenylpyridine copolymer with pendant carbazole groups

“…Rather than encoding '0' and '1' as the amount of charge stored in a cell, a polymer memory stores data in another form, based on the high-and low-conductivity response to an applied voltage (electrical bistability; Raymo 2002). In the earlier fine works on polymer memory effects, both volatile and non-volatile memory effects based on bistable electrical conductivity switching have been observed (Bandhopadhyay & Pal 2003;Bozano et al 2005;Paul et al 2006;Verbakel et al 2006;Wang et al 2006;Yang et al 2006). Recently, multi-level conductance switching in polymer films has also been demonstrated (Lauters et al 2006).…”