Field-induced nucleation in phase change memory

Abstract

A theory of field-induced crystal nucleation is developed and verified experimentally for the case of switching in nanoglasses of phase change memory. For symmetry-breaking strong electric fields, it predicts needleshaped crystallites with nucleation barriers lower than that of spherical nuclei and a strong field dependent. We have observed bias dependent switching for times and temperatures far beyond those typically reported and supportive of our predictions, in particular, switching time exponential in voltage and temperature.

Comment on “Threshold switching via electric field induced crystallization in phase change memory devices” [Appl. Phys. Lett. 100, 253105 (2012)]

“…We find the conclusion of Diosdado 1 and the underlying approaches 2,3 to be unjustified and misrepresenting our proposed mechanism of FIN, [4][5][6][7][8][9][10] as explained below.…”

“…For the typical material parameters, one can estimate E 0 $ 10 6 À 10 7 V=cm and E c $ 3 Â 10 4 À 3 Â 10 5 V=cm, the latter well in the range of experimentally observed switching. 5,6 This is illustrated in Fig. 1.…”

“…The work by Diosdado 1 is limited to spherical particles, thereby ignoring the main content of FIN theory [4][5][6][7][8][9][10] that the field effect is dominated by elongated particles. As a result, the estimate by Diosdado 1 is related to E 0 and not to the experimentally relevant E $ E c ( E 0 .…”

“…Based on the experimental data, [5][6][7] it was estimated that a $ 0:1. Because of E c ( E 0 , FIN becomes important under much lower fields for strongly elongated nuclei than for spherical nuclei.…”

On the stochastic nature of resistive switching in Cu doped Ge0.3Se0.7 based memory devices

“…Following the approach of the high field induced nucleation model for threshold switching behavior in PCRAM, as proposed by Kaprov et al, 41,42 the nucleation time varies as…”