Effect of Ion-implantation on Forming and Resistive-Switching Response of NiO Thin films
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1250-G05-06
Effect of Ion-implantation on Forming and Resistive-Switching Response of NiO Thin films
Robert G. Elliman, Muhammad N. Saleh, Sung Kim, Dinesh K. Venkatachalam, Taehyun Kim and Kidane Belay Electronic Materials Engineering Department, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200, Australia ABSTRACT The forming voltage and set/reset response of sputter-deposited NiO thin films is studied as a function of implant fluence for samples implanted with Ni and O ions. The forming voltage of the films is shown to decrease with increasing ion fluence and to scale with the damage production rate of the different ions. In contrast, the set/reset response of the films was largely unaffected by the ion-implantation. These results are discussed in terms of the filamentary model of conduction and the thermochemical model of resistive switching. INTRODUCTION Resistive switching is a process in which the resistance of a dielectric thin film is repeatedly switched between low and high resistance states by the application of appropriate current-voltage pulses, and is believed to result from the local breaking and reforming of conductive filaments produced by the initial voltage stress (forming process). This process was first reported more than fifty years ago [1-3] but has recently received renewed attention because of its potential for fabricating non-volatile memory devices [4-5]. However, in order to fully exploit it the atomic mechanisms responsible for the switching behavior must be understood. Many models for have been proposed, including trap charging in the dielectric, space-chargelimited conduction processes, ion conduction and electrodeposition, Mott transition, and Jouleheating effects. In some cases, such as TiO2, the understanding is now highly developed [6] while in others the understanding remains rudimentary and/or speculative. NiO is particularly attractive for non-volatile memory applications due to its high-speed, low power switching characteristics and its CMOS compatibility [7-9]. Resistive switching in this case is thought to be based on a thermochemical process in which a conductive filament formed by field-induced defects is broken (reset) by defect annealing caused by local Joule heating [10-12]. The electrical properties of NiO are a sensitive function of the film stoichiometry, and O-vacancies are known to play a significant role in determining such properties. The presence of metallic impurities, such as Ti or Li, is also known to affect the switching characteristics [13-14]. Ion-implantation can be used to controllably introduce defects and/or impurities into different regions of thin film structures and therefore provides a useful tool for studying the influence of such parameters on resistive switching. In this study we examine the effect of Ni and O ion-implantation on the forming voltage and set/reset response of NiO thin films.
EXPERIMENTAL Metal-insulator-metal test structures were fabricated on oxidized (300nm thermal oxide) (100) Si
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