TY - JOUR
T1 - Nanoscale cation motion in TaOx, HfOx and TiOx memristive systems
AU - Wedig, Anja
AU - Luebben, Michael
AU - Cho, Deok Yong
AU - Moors, Marco
AU - Skaja, Katharina
AU - Rana, Vikas
AU - Hasegawa, Tsuyoshi
AU - Adepalli, Kiran K.
AU - Yildiz, Bilge
AU - Waser, Rainer
AU - Valov, Ilia
N1 - Funding Information:
This study was financially supported in part by BMBF project no. 03X0140 and DFG priority programme SFB 917. B.Y. and K.K.A. also acknowledge financial support from the MIT MRSEC through the MRSEC Program of the National Science Foundation under award no. DMR-1419807.
Publisher Copyright:
© 2016 Macmillan Publishers Limited. All rights reserved.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - A detailed understanding of the resistive switching mechanisms that operate in redox-based resistive random-access memories (ReRAM) is key to controlling these memristive devices and formulating appropriate design rules. Based on distinct fundamental switching mechanisms, two types of ReRAM have emerged: electrochemical metallization memories, in which the mobile species is thought to be metal cations, and valence change memories, in which the mobile species is thought to be oxygen anions (or positively charged oxygen vacancies). Here we show, using scanning tunnelling microscopy and supported by potentiodynamic current-voltage measurements, that in three typical valence change memory materials (TaOx, HfOx and TiOx) the host metal cations are mobile in films of 2 nm thickness. The cations can form metallic filaments and participate in the resistive switching process, illustrating that there is a bridge between the electrochemical metallization mechanism and the valence change mechanism. Reset/Set operations are, we suggest, driven by oxidation (passivation) and reduction reactions. For the Ta/Ta2 O5 system, a rutile-type TaO2 film is believed to mediate switching, and we show that devices can be switched from a valence change mode to an electrochemical metallization mode by introducing an intermediate layer of amorphous carbon.
AB - A detailed understanding of the resistive switching mechanisms that operate in redox-based resistive random-access memories (ReRAM) is key to controlling these memristive devices and formulating appropriate design rules. Based on distinct fundamental switching mechanisms, two types of ReRAM have emerged: electrochemical metallization memories, in which the mobile species is thought to be metal cations, and valence change memories, in which the mobile species is thought to be oxygen anions (or positively charged oxygen vacancies). Here we show, using scanning tunnelling microscopy and supported by potentiodynamic current-voltage measurements, that in three typical valence change memory materials (TaOx, HfOx and TiOx) the host metal cations are mobile in films of 2 nm thickness. The cations can form metallic filaments and participate in the resistive switching process, illustrating that there is a bridge between the electrochemical metallization mechanism and the valence change mechanism. Reset/Set operations are, we suggest, driven by oxidation (passivation) and reduction reactions. For the Ta/Ta2 O5 system, a rutile-type TaO2 film is believed to mediate switching, and we show that devices can be switched from a valence change mode to an electrochemical metallization mode by introducing an intermediate layer of amorphous carbon.
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U2 - 10.1038/nnano.2015.221
DO - 10.1038/nnano.2015.221
M3 - Article
AN - SCOPUS:84954370515
SN - 1748-3387
VL - 11
SP - 67
EP - 74
JO - Nature Nanotechnology
JF - Nature Nanotechnology
IS - 1
ER -