Comparison of resistive switching characteristics using copper and aluminum electrodes on GeOx/W cross-point memories

Sheikh Ziaur Rahaman,Siddheswar Maikap

doi:10.1186/1556-276x-8-509

Abstract

Comparison of resistive switching memory characteristics using copper (Cu) and aluminum (Al) electrodes on GeOx/W cross-points has been reported under low current compliances (CCs) of 1 nA to 50 μA. The cross-point memory devices are observed by high-resolution transmission electron microscopy (HRTEM). Improved memory characteristics are observed for the Cu/GeOx/W structures as compared to the Al/GeOx/W cross-points owing to AlOx formation at the Al/GeOx interface. The RESET current increases with the increase of the CCs varying from 1 nA to 50 μA for the Cu electrode devices, while the RESET current is high (>1 mA) and independent of CCs varying from 1 nA to 500 μA for the Al electrode devices. An extra formation voltage is needed for the Al/GeOx/W devices, while a low operation voltage of ±2 V is needed for the Cu/GeOx/W cross-point devices. Repeatable bipolar resistive switching characteristics of the Cu/GeOx/W cross-point memory devices are observed with CC varying from 1 nA to 50 μA, and unipolar resistive switching is observed with CC >100 μA. High resistance ratios of 102 to 104 for the bipolar mode (CCs of 1 nA to 50 μA) and approximately 108 for the unipolar mode are obtained for the Cu/GeOx/W cross-points. In addition, repeatable switching cycles and data retention of 103 s are observed under a low current of 1 nA for future low-power, high-density, nonvolatile, nanoscale memory applications.

Highlights

Resistive switching memory devices involving different materials such as Pr0.7Ca0.3MnO3 (PCMO) [1], NiOx [2], SrTiO3 [3,4], TaOx [5,6,7,8], HfOx [9,10], TiO2 [11], ZrO2 [12], Na0.5Bi0.5TiO3 [13], and AlOx [14,15,16] are widely reported to replace conventional flash memory
This suggests that Al is a metal reactive with oxygen, and it is hard to control the reaction at the Al/oxide interface
Improved memory characteristics of the Cu/GeOx/W structures under low current varying from 1 nA to 50 μA and a low voltage operation of ±2 V are observed as compared to those of the Al/GeOx/W structures

Summary

Introduction

Resistive switching memory devices involving different materials such as Pr0.7Ca0.3MnO3 (PCMO) [1], NiOx [2], SrTiO3 [3,4], TaOx [5,6,7,8], HfOx [9,10], TiO2 [11], ZrO2 [12], Na0.5Bi0.5TiO3 [13], and AlOx [14,15,16] are widely reported to replace conventional flash memory. Conductive bridging resistive random access memory (CBRAM) involving the migration of cations (Ag+ or Cuz+, z = 1, 2) in solid electrolytes such as GexSe1−x [17,18,19,20], GeS2 [21], Ta2O5 [22], ZrO2 [23,24,25], TiOx/ZrO2 [26], GeSex/TaOx [27], HfO2 [28], CuTe/Al2O3 [29], Ti/TaOx [30], ZnO [31], SiO2 [32], and GeOx [33] is reported. A cross-point memory using a Cu/GeOx/W structure has been compared with that using an Al/GeOx/W structure for the first time

Methods

Results

Conclusion