Encontrados 12 documentos, a visualizar página 1 de 2
Dynamic behavior of resistive random access memories (RRAMS) based on plastic s...
Rocha, P. R. F.; Kiazadeh, A.; Chen, Q.; Gomes, Henrique L.Resistive Random Access Memories based on metal-oxide polymer diodes are characterized. The dynamic behavior is studied by recording current-voltage characteristics with varying voltage ramp speed. It is demonstrated that these organic memory devices have an internal capacitive double-layer structure, which inhibits the switching at high ramp rates (1000 V/s). This behavior is modeled and explained in terms of ...
Electroforming process in metal-oxide-polymer resistive switching memories
Chen, Q.; Gomes, Henrique L.; Kiazadeh, A.; Rocha, P. R. F.; De Leeuw, Dago M.; Meskers, S. C. J.Electroforming of an Al/Al2O3/polymer/Al esistive switching diode is reported. Electroforming is a dielectric soft-breakdown mechanism leading to hysteretic current–voltage characteristics and non–volatile memory behavior. Electron trapping occurs at early stages of electroforming. Trapping is physically located at the oxide/polymer interface. The detrapping kinetics is faster under reverse bias and for thicker...
New electronic memory device concepts based on metal oxide-polymer nanostructur...
Kiazadeh, A.; Rocha, P. R. F.; Chen, Q.; Gomes, Henrique L.Nanostructure silver oxide thin films diodes can exhibit resistive switching effects. After an electroforming process the device can be programmed between a low conductance (off-state) and high conductance (on- state) with a voltage pulse and they are already being considered for non-volatile memory applications. However, the origin of programmable resistivity changes in a network of nanostructure silver oxide ...
Planar non-volatile memory based on metal nanoparticles
Kiazadeh, A.; Gomes, Henrique L.; Costa, Ana M. Rosa da; Rocha, P. R. F.; Chen, Q.; Moreira, José A.; De Leeuw, Dago M.; Meskers, S. C. J.Resistive switching properties of silver nanoparticles hosted in an insulating polymer matrix (poly(N-vinyl-2-pyrrolidone) are reported. Planar devices structures using interdigitated gold electrodes were fabricated. These devices have on/off resistance ratio as high as 103 , retention times reaching to months and good endurance cycles. Temperature-dependent measurements show that the charge transport is weakly...
Opto-electronic characterization of electron traps upon forming polymer oxide m...
Chen, Q.; Bory, Benjamin F.; Kiazadeh, A.; Rocha, P. R. F.; Gomes, Henrique L.; Verbakel, F.; De Leeuw, Dago M.; Meskers, S. C. J.Metal-insulator-polymer diodes where the insulator is a thin oxide (Al2O3) layer are electroformed by applying a high bias. The initial stage is reversible and involves trapping of electrons near the oxide/polymer interface. The rate of charge trapping is limited by electron transport through the polymer. Detrapping of charge stored can be accomplished by illuminating with light under short-circuit conditions. ...
Doping distribution of an operating organic light-emitting diode: a raman map a...
Paez-Sierra, B. A.; Gomes, Henrique L.; Rangel-Kuoppa, V.T.We present confocal Raman spectroscopy (CSRS) maps of Poly(9,9-dioctylfluorene) (PFO)-based organic light emitting diode under operation. The CSRS analysis of the OLEDs was performed in normal room conditions. The non-emissive spots presented higher Raman intensity and broadening of the vibrational bands in comparison with the luminescent ones. The phenomenon is associated with an increase in the PFO - * absor...
Trapping of electrons in metal oxide-polymer memory diodes in the initial stage...
Bory, Benjamin F.; Meskers, S. C. J.; Janssen, R. A. J.; Gomes, Henrique L.; De Leeuw, Dago M.Metal oxide-polymer diodes require electroforming before they act as nonvolatile resistive switching memory diodes. Here we investigate the early stages of the electroforming process in Al/Al2O3 /polyspirofluorene /Ba/Al diodes using quasistatic capacitance-voltage measurements. In the initial stage, electrons are injected into the polymer and then deeply trapped near the polyspirofluorene-Al2O3 interface. For ...
Confocal scanning raman spectroscopy (CSRS) of an operating organic light-emitt...
Paez-Sierra, B. A.; Gomes, Henrique L.Organic molecules with semiconducting properties are becoming nowadays core of the organic-based electronic era. Although organic light emitting diodes (OLEDs) have already matured for commercial applications, they still require longer device lifetimes. Some of the long-standing challenges in OLED technology relay on degradation and failure mechanisms. Several authors observed that degradation and subsequent da...
Gate-bias stress in amorphous oxide semiconductors thin-film transistors
Lopes, M. E.; Gomes, Henrique L.; Medeiros, M. C. R.; Barquinha, P.; Pereira, L. M. C.; Fortunato, E.; Martins, R.; Ferreira, I.A quantitative study of the dynamics of threshold-voltage shifts with time in gallium-indium zinc oxide amorphous thin-film transistors is presented using standard analysis based on the stretched exponential relaxation. For devices using thermal silicon oxide as gate dielectric, the relaxation time is 3 105 s at room temperature with activation energy of 0.68 eV. These transistors approach the stability of the ...
Magnetic and transport properties of diluted granular multilayers
Silva, H. G.; Gomes, Henrique L.; Pogorelov, Y. G.; Pereira, L. M. C.; Kakazei, G. N.; Sousa, J. B.; Araújo, J. P.; Mariano, J. F. L.; Cardoso, S.The magnetic and transport properties of Co80Fe20t /Al2O34 nm multilayers with low nominal thicknesses t=0.7 and 0.9 nm of Co80Fe20 granular layers are studied. Magnetic studies find a superparamagnetic state above the blocking temperature Tb of field-cooled/zero-field-cooled splitting that grows with t and decreases with H. The low-voltage Ohmic tunnel transport passes to non-Ohmic IV3/2 law for applied fields...
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