Circuit demonstration of radiation hardened chalcogenide non-volatile memory

Maimon, J.; Hunt, K.; Rodgers, J.; Burcin, L.; Knowles, K.

doi:10.1109/aero.2003.1235161

Cited by 10 publications

(4 citation statements)

References 15 publications

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“…[1][2][3][4][5][6][7][8][9][10] In both the optical and electrical phase-change data storage methods, data are written by locally melt quenching the crystalline phase-change film into an amorphous state using an optical ͑laser͒ or electrical pulse. The written amorphous bit can be read due to its large optical ͑reflectivity͒ or electrical ͑resistivity͒ contrast with the surrounding crystalline background.…”

Section: Influence Of Capping Layers On the Crystallization Of Doped mentioning

confidence: 99%

Influence of capping layers on the crystallization of doped SbxTe fast-growth phase-change films

Pandian

Kooi

Hosson

et al. 2006

Journal of Applied Physics

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Isothermal crystallization of doped Sb x Te fast-growth phase-change films, with and without capping layers, was investigated using transmission electron microscopy, which provided direct and quantitative information on nucleation and growth processes separately. Two types of amorphous dielectric layers, ZnS -SiO 2 and GeCrN, were used for sandwiching the Sb x Te films to form typical trilayer stacks, which are the active part in applications. The nucleation and growth parameters of Sb x Te films were found to be influenced by the dielectric capping layers. The crystal growth rate is temperature dependent and it reduces when the film is sandwiched between the dielectric layers. The reduction in growth rate differs with the capping layer type. The capping layer influence on the growth rate is pronounced at lower temperatures ϳ160°C, but tends to vanish at higher temperatures ϳ200°C. The activation energy for crystal growth is 2.4± 0.3 eV for an uncapped film and it increases ϳ40% when the capping layers, GeCrN or ZnS -SiO 2 , are added. A temperature and time dependent nucleation rate is found and it is accelerated ϳ1.7 times by GeCrN layers, whereas it is retarded ϳ5 times by ZnS -SiO 2 layers. The activation energy for crystal nucleation is 6.1± 0.4 eV for an uncapped film and it is not noticeably altered by the capping layers. These variations observed in the crystallization kinetics are attributed to variations in interface energy between the phase-change film and the capping layers or vacuum and the confinement effect by the capping layers on the phase-change film.

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Section: Influence Of Capping Layers On the Crystallization Of Doped mentioning

confidence: 99%

Influence of capping layers on the crystallization of doped SbxTe fast-growth phase-change films

Pandian

Kooi

Hosson

et al. 2006

Journal of Applied Physics

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“…In recent years, the main focus of phase-change data-storage research returned to resistance switching. So-called chalcogenide or phase-change random access memory (CRAM/PRAM) and ovonic unified memory (OUM) based on the phase-dependent resistance switching are currently under intense investigations, [5][6][7][8][9][10][11][12][13] because they show great promise as next-generation nonvolatile solid-state memory replacing flash memory. In certain chalcogenides a special phenomenon of polaritydependent resistance switching (induced by an electric field) has been identified.…”

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confidence: 99%

Nanoscale Electrolytic Switching in Phase‐Change Chalcogenide Films

et al. 2007

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This Communication presents the important finding that certain chalcogenide materials, well-known from rewritable optical recording, allow resistive memory states that are a combination of two electrically-induced (reversible) switching processes, i.e., an actual amorphous-crystalline phase transformation and a (electrolytic) polarity-dependent resistance change. Nanometer-sized crystalline marks were written electrically in amorphous Ge 2 Sb 2+x Te 5 films using atomic force microscopy (AFM), and their resistance was found to depend on the polarity of the applied voltage with a resistance difference of three orders of magnitude. However, no contrast in current has been detected between the crystalline higherresistance state and the surrounding amorphous phase. This resistance switching is reversible for bias voltages well below the threshold voltage required to induce the phase transformation. The switching mechanism is attributed to the solidstate electrolytic behavior due to the presence of excess Sb in the films. Our results render exciting technological opportunities for data storage and encryption by combining both switching concepts.Following his seminal work in 1968, [1] Ovshinsky demonstrated in chalcogenide alloys a fast reversible transformation between amorphous and crystalline phases induced by electrical or optical (laser) pulses. [2][3][4] The two phases exhibited clear contrast in electrical and optical properties and, hence, these materials were suggested for binary data-storage applications. However, it took considerable time before rewritable optical compact discs (CD) and digital versatile discs (DVD) based on these findings came to the market. In recent years, the main focus of phase-change data-storage research returned to resistance switching. So-called chalcogenide or phase-change random access memory (CRAM/PRAM) and ovonic unified memory (OUM) based on the phase-dependent resistance switching are currently under intense investigations, [5][6][7][8][9][10][11][12][13] because they show great promise as next-generation nonvolatile solid-state memory replacing flash memory. In certain chalcogenides a special phenomenon of polaritydependent resistance switching (induced by an electric field) has been identified. [14][15][16][17][18][19] This is related to the solid-state electrolytic character and high ionic conductivities of chalcogenides, and hence is called ionic/electrolytic switching. For one polarity, the chalcogenide medium is electrically conductive by forming conducting filamentary pathways between electrodes, whereas for the reverse polarity it becomes relatively insulative or at least less conductive because of rupture of the previously formed electrical pathways. Memory elements (or structures) based on this switching have been demonstrated in some Ag-saturated chalcogenides including Ag-S, [14,15] AgGe-Se, [16,17] Ag-Ge-Te, [18] and Ag-In-Sb-Te. [19] This switching seems more attractive for applications than phase-dependent switching, because i) it can be performed at lower volta...

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“…The crystalline and amorphous states of chalcogenide materials have dramatically different reflectivity values, which forms the basis by which data are stored. Ge-Sb-Te system is one of the most commonly used chalcogenide-based phase-change material used in the rewritable storage media due to its excellent properties with respect to thermal stability, cyclability and crystallization speed [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%