This journal is © The Royal Society of Chemistry 2016 J. Mater. Chem. C Cite this: DOI: 10.1039/c6tc03607d Resistive switching characteristics of all-solution-based Ag/TiO 2 /Mo-doped In 2 O 3 devices for non-volatile memory applications† Sujaya Kumar Vishwanath and Jihoon Kim* In this paper, we demonstrate the fabrication of electrochemical-metallization-based resistive switching random access memory (ECM-based ReRAM) devices with an Ag/TiO 2 /Mo-doped In 2 O 3 configuration through a simple solution-based process. Both TiO 2 and Mo-doped In 2 O 3 layers in the memory device were spin-coated with polymer-assisted-solution inks formulated by coordinating the Ti-, Mo-, and In- complex with a water-soluble polymer. The Ag top electrode was inkjet-printed with Ag nanoparticle ink. The memory devices fabricated by all-solution processes demonstrated excellent bipolar switching behavior with a high resistive switching ratio of 10 3 , an excellent endurance of more than 1000 cycles, a stable retention time greater than 10 4 s at elevated temperatures, and a fast programming speed of 250 ns. The characterization results of the conduction mechanism in high and low resistive states indicate that the resistive switching is caused by the formation and rupture of nano-sized Ag conducting filaments in the TiO 2 layer. These results suggest the potential of all-solution-based ECM-based ReRAM for developing future nonvolatile memory devices at low cost. Introduction The new environment of future electronics requires higher computing power and higher energy efficiency. Thus, there is an emerging demand for new memory devices with better endurance, faster programming speed, and lower power consumption. 1–9 The scalability issues of modern floating-gate-based flash memory devices emerge as a major concern to achieve these goals in the semiconductor industry, due to the technical limit of floating gates when managing electrons in further scaled-down devices. In order to address these challenges, alternative nonvolatile memory architectures have been investigated such as devices based on ferroelectric polarization (FRAM: ferroelectric random access memory), magnetic polarization (MRAM: magnetic random access memory) and material phase change (PRAM: phase- change random access memory). However, these new memory concepts still suffer from miniaturization and power consumption issues. 10,11 Under these circumstances, another nonvolatile memory concept based on resistive switching by external electrical stimulation (ReRAM: resistive-switching random access memory) has attracted significant attention. These devices present high scalability with a simple cross-bar memory structure (4F 2 /n compaction where F and n are the minimal feature size and the number of vertical stacking layers, respectively), high switching speed (o10 ns), high endurance (410 7 cycles), good retention time (410 years at 85 1C), and low power consump- tion (B1 mW). 5,9,12,13 ReRAM devices consist of a simple capacitor-like structure, with an insulating layer in between two conducting electrodes. The origin of resistive switching in ReRAMs is usually attributed to the formation and rupture processes of nano-size conducting filaments (CFs) in the insulating layer, leading to low (SET) and high (RESET) resistive states in the ReRAM structure. The choice of electrode materials plays a key role in forming CFs in the insulating layer. With the asymmetric combination of an electro- chemically active electrode (Ag or Cu) and an electrochemically inert electrode (Pt, Au, W, etc.), CFs are formed by the electro- chemical dissolution and ionic migration of the electrochemically active materials, triggered by a sufficient bias voltage with proper polarity. The ReRAM operated by this specific mechanism is called electrochemical-metallization (ECM) memory. Many different types of materials, such as perovskites, chalcogenides and metal oxides, have been explored to be applied as insulating layers. 14–23 Recently, binary transition metal oxides such as TiO 2 , Cu 2 O, NiO, Ta 2 O 5 , Al 2 O 3 and Nb 2 O 5 have been extensively investigated due to their simple composition and thermal stability. However, in most cases, the insulating layer and the conducting electrodes are deposited using vacuum-based processes including Division of Advanced Materials Engineering, Kongju National University, Cheoan-daero, Seobuk-gu, Cheonan, Chunganm, 31080, Korea. E-mail: Jihoon.Kim@kongju.ac.kr † Electronic supplementary information (ESI) available. See DOI: 10.1039/ c6tc03607d Received 21st August 2016, Accepted 30th October 2016 DOI: 10.1039/c6tc03607d www.rsc.org/MaterialsC Journal of Materials Chemistry C PAPER Published on 31 October 2016. Downloaded by Kongju National University on 11/11/2016 13:23:48. View Article Online View Journal