Patel, K;
Cottom, J;
Bosman, M;
Kenyon, AJ;
Shluger, AL;
(2019)
An oxygen vacancy mediated Ag reduction and nucleation mechanism in SiO2 RRAM devices.
Microelectronics Reliability
, 98
pp. 144-152.
10.1016/j.microrel.2019.05.005.
Preview |
Text
MR-Final-KP2.pdf - Accepted Version Download (764kB) | Preview |
Abstract
Density Functional Theory (DFT) calculations were used to model the incorporation and diffusion of Ag in Ag/SiO 2 /Me (Me = W or Pt) resistive random-access memory (RRAM) devices. We consider an O vacancy (V O ) mediated model of the initial stages of Ag clustering, where the V O is identified as the principle site for Ag + reduction. The Ag + interstitial is calculated to be energetically favoured inside a-SiO 2 at the Fermi energies of Ag, W and Pt. The adiabatic diffusion barriers of Ag + are found to be lower than those for Ag 0 with a strong dependence on the local network structure, supporting Ag + being the mobile species during device operation. Ag + ions bind to V O forming the [Ag/V O ] + complex. The [Ag/V O ] + complex is then reduced by trapping an electron forming [Ag/V O ] 0 . By sampling every V O in a 216-atom cell of a-SiO 2 we demonstrate that this mechanism can occur only at 33%, 33% and 11% of O vacancies at the Ag, W and Pt electrodes, respectively. This complex can subsequently act as a nucleation site for Ag clustering with the formation of [Ag 2 /V O ] + , which is reduced by trapping an extra electron.
Archive Staff Only
 |
View Item |
