Structure and behavior of ZrO2-graphene-ZrO2 stacks

Tauno Kahro,Aile Tamm,Salvador Dueñas,Kaupo Kukli,Helena Castán,Aarne Kasikov,Jekaterina Kozlova,Joonas Merisalu,Helle-Mai Piirsoo,Hugo Mändar,Peeter Ritslaid,Aivar Tarre,Taivo Jõgiaas

doi:10.1116/6.0000390

Abstract

ZrO2-graphene-ZrO2 layered structures were built and their crystallinity was characterized before resistive switching measurements. Thin nanocrystalline ZrO2 dielectric films were grown by atomic layer deposition on chemical vapor deposited graphene. Graphene was transferred, prior to the growth of the ZrO2 overlayer, to the ZrO2 film pre-grown on titanium nitride. Nucleation and growth of the top ZrO2 layer was improved after growing an amorphous Al2O3 interface layer on graphene at lowered temperatures. Studies on resistive switching in such structures revealed that the exploitation of graphene interlayers could modify the operational voltage ranges and somewhat increase the ratio between high and low resistance states.

Highlights

Application of graphene, either directly deposited or transferred on other thin films functional in different devices,[1,2] has emerged as one of the major, focused, directions in the research and development of novel materials relevant to nanotechnology
Considering the knowledge gained earlier on resistive switching media formed on the basis of either ZrO2 or graphene, combinations of ZrO2 layers grown using atomic layer deposition with graphene obtained by chemical vapor deposition method and transferred between ZrO2 host layers may open up a new possibility when seeking routes to low-cost and flexible resistive random-access memories (RERAM) cells, provided that the fabrication processes of component layers can further be developed
Morphology and Raman shift measurements revealed that the deposition of a ZrO2 film on graphene did not affect the quality of graphene, whereas in the case of an Al2O3 interfacial layer deposited on graphene prior to the growth of ZrO2, the possible doping effect on graphene was more pronounced and the nucleation of ZrO2 somewhat enhanced

Summary

INTRODUCTION

Application of graphene, either directly deposited or transferred on other thin films functional in different devices,[1,2] has emerged as one of the major, focused, directions in the research and development of novel materials relevant to nanotechnology. To enhance resistive switching (RS) performance in a ZrO2-based RERAM, Mo (Ref. 25) or thin TiOx layers[26] have been embedded in ZrO2 host films It has been noticed some time ago that a combination of relatively conductive and relatively better insulating materials, if deposited alternately, can provide decrement in the forming voltage to the level of switching voltages. Considering the knowledge gained earlier on resistive switching media formed on the basis of either ZrO2 or graphene, combinations of ZrO2 layers grown using atomic layer deposition with graphene obtained by chemical vapor deposition method and transferred between ZrO2 host layers may open up a new possibility when seeking routes to low-cost and flexible RERAM cells, provided that the fabrication processes of component layers can further be developed. It was necessary to examine whether the application of graphene in a ZrO2-based medium can modify the parameters of resistive switching and, possibly, allow multilevel switching on RERAM-like structures

EXPERIMENT

Morphology and structure

Electrical behavior

SUMMARY AND CONCLUSIONS