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Programming Current Reduction via Enhanced Asymmetry-Induced Thermoelectric Effects in Vertical Nanopillar Phase-Change Memory Cells

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Title Programming Current Reduction via Enhanced Asymmetry-Induced Thermoelectric Effects in Vertical Nanopillar Phase-Change Memory Cells
 
Creator BAHL, J
RAJENDRAN, B
MURALIDHARAN, B
 
Subject NONVOLATILE MEMORY
RESISTANCE
DEVICES
FILMS
Asymmetry
nanopillar
phase-change memory (PCM)
programming current
thermoelectric
 
Description Thermoelectric effects are envisioned to reduce programming currents in nanopillar phase-change memory (PCM) cells. However, due to the inherent symmetry in such a structure, the contribution due to thermoelectric effects on programming currents is minimal. In this paper, we propose a hybrid PCM structure, which incorporates a twofold asymmetry specifically aimed to favorably enhance the thermoelectric effects. The first asymmetry is introduced via an interface layer of low thermal conductivity and high negative Seebeck coefficient, such as polycrystalline SiGe, between the bottom electrode contact and the active region comprising the phase-change material. This results in an enhanced Peltier heating of the active material. The second one is introduced structurally via a taper that results in an angle-dependent Thomson heating within the active region. Various device geometries are analyzed using 2-D-axis-symmetric simulations to predict the effect on programming currents as well as for different thicknesses of the interface layer. A programming current reduction of up to 60% is predicted for specific cell geometries. Remarkably, we find that due to an interplay of Thomson cooling in the electrode and the asymmetric heating profile inside the active region, the predicted programming current reduction is resilient to fabrication variability.
 
Publisher IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
 
Date 2016-01-15T09:12:38Z
2016-01-15T09:12:38Z
2015
 
Type Article
 
Identifier IEEE TRANSACTIONS ON ELECTRON DEVICES, 62(12)4015-4021
0018-9383
1557-9646
http://dx.doi.org/10.1109/TED.2015.2486142
http://dspace.library.iitb.ac.in/jspui/handle/100/18245
 
Language en