1,720,988 research outputs found
Fast detrapping transients in high-k dielectric films
No full textCharge trapping and detrapping are mechanisms which substantially modify dynamically the electric features of high-k dielectrics and cause instability of the MOS flat band voltage. The timescale on which such phenomena take place depends on the space and energy distribution of traps and in high-k dielectrics it may span on a very wide interval. On the other hand, conventional electrical measurements operating in stationary conditions take several seconds, thus affecting the measurement result and inhibiting from monitoring charge transients at shorter times. In this work, we present a detailed investigation of flat band transients due to charge detrapping in Cl 2O 3 films designed for nonvolatile applications, on a timescale spanning from hundreds of microseconds to ten minutes. For this purpose, a technique based on the pulsed C-V measurement has been used. The flat band voltage instability due to charge detrapping has been studied systematically. © The Electrochemical Society
Forming kinetics in HfO2-Based RRAM cells
No full textIn this paper, key aspects of the electroforming in resistive-RAM cells with HfO2 are addressed. Specifically, transient measurements were performed on extremely short timescales to characterize systematically the forming time as a function of the voltage pulse amplitude, temperature, electrode materials, and device area. An analytical model was developed, accounting for the investigated experimental parameters. Impact of the forming (and SET) waveform on read disturb is also investigated. © 1963-2012 IEEE
Threshold voltage instability in high-k based flash memories
No full textIn this work we use an innovative transient technique based on the pulsed C-V measurement and present detailed investigation and simulation of threshold voltage instability in Al2O3 flash memories, on a time-scale spanning from hundreds of microseconds to ten minutes. Advantages of the pulsed over the steady-state C-V technique lye in that it can monitor capacitance transients at extremely short times, and it does not affect the flat-band condition itself, since the measurement time is short enough that trapping during the measurement does not occur. The flat-band voltage instability has been studied systematically as a function of the film thickness, the detrapping time and the discharge accelerating voltage. A detailed description of the detrapping dynamics is given. (C) 2010 Elsevier Ltd. All rights reserved
Detrapping dynamics in Al2O3 metal-oxide-semiconductor
No full textIn this paper, we use a two-pulse C-V technique to study detrapping in Al2O3 metal-oxide-semiconductor at extremely short (and long) times. The investigated timescale spanned from hundreds of microseconds to ten minutes. The flat band voltage instability was studied systematically and a phenomenological model was written which accounts for logarithmic dependence on time, and linear dependence on the film thickness and the accelerating voltage. A main goal of the work is to demonstrate that this technique is a tool for the investigation of fast electrical transients in high-k films on timescale which are not accessible with conventional steady-state techniques. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3369335
Conductive filament evolution in HfO2 resistive RAM device during constant voltage stress
No full textThe resistance evolution under constant voltage stress of the low resistive state and the high resistive state of HfO2 based RRAM cells is studied from an experimental and theoretical point of view. A filamentary model based on ions hopping and oxygen vacancies generation phenomena is used to interpret the behavior of the cells. The gap between the tip of the filament and the metal electrode is the parameter governing the device resistance. The current experiments are simulated in terms of the time evolution of the gap length during the electrical stress. The impact of the stress voltage amplitude and the parameter variability on the degradation dynamics is emphasized
Electrical instability in LaLuO3 based metal-oxide-semiconductor capacitors and role of the metal electrodes
No full textTrapping in LaLuO3 MOS capacitors with different metal nitride gates is investigated for the first time. The instability of the flat band voltage during electrical stress is monitored systematically with the pulsed C-V technique as function of stress time and voltage. Ad-hoc experiments aiming to force electron trapping in sites close to the metal/high-k interface are performed, and the role of different metal nitride gates is discussed. Trapping exhibits a power-law dependence on stress time in any investigated condition. Interpolation of the experimental data with an analytical model of trapping allows extraction of the energy level of traps involved in the capture mechanism. (C) 2013 American Vacuum Society. [http://dx.doi.org/10.1116/1.4774105
Trapping in high-k dielectrics
No full textIn this paper, an analytical model of trapping in high-k dielectrics is proposed. It starts from the general rate equation and relies on the hypothesis that the density of states involved in the capture mechanism follows a Fermi-like distribution. Thus, the energy depth of the trap level respect to the Fermi level is explicited in the model. The model is validated comparing predictions of flat band shift (calculated integrating the density of involved states) with experimental curves measured on GdSiO metal-oxide-semiconductor capacitors in many different conditions. The energy level of the trap is extracted. (C) 2010 American Institute of Physics. [doi:10.1063/1.3503583
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