Fully Room-Temperature-Fabricated Nonvolatile Resistive Memory for Ultrafast and High-Density Memory Application Yu Chao Yang, † Feng Pan,* ,† Qi Liu, ‡ Ming Liu, ‡ and Fei Zeng † Laboratory of AdVanced Materials, Department of Materials Science and Engineering, Tsinghua UniVersity, Beijing 100084, People’s Republic of China, and Laboratory of Nano-fabrication and NoVel DeVices Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, People’s Republic of China Received January 1, 2009; Revised Manuscript Received February 16, 2009 ABSTRACT Through a simple industrialized technique which was completely fulfilled at room temperature, we have developed a kind of promising nonvolatile resistive switching memory consisting of Ag/ZnO:Mn/Pt with ultrafast programming speed of 5 ns, an ultrahigh R OFF /R ON ratio of 10 7 , long retention time of more than 10 7 s, good endurance, and high reliability at elevated temperatures. Furthermore, we have successfully captured clear visualization of nanoscale Ag bridges penetrating through the storage medium, which could account for the high conductivity in the ON-state device. A model concerning redox reaction mediated formation and rupture of Ag bridges is therefore suggested to explain the memory effect. The Ag/ZnO:Mn/Pt device represents an ultrafast and highly scalable (down to sub-100-nm range) memory element for developing next generation nonvolatile memories. The semiconductor industry has long been seeking a high- density, high-speed, and low-power memory technology that retains its data even when the power is interrupted. 1 Though static random access memory (SRAM) and dynamic random access memory (DRAM) are very fast, both of them are volatile, which is a huge disadvantage, costing energy and additional periphery circuitry. Traditional nonvolatile flash memory based on charge storage is rapidly approaching its fundamental scaling limit due to the increasing difficulty of retaining electrons in shrinking dimensions. Moreover, it requires relatively long write time (>1 μs). Magnetic random access memory (MRAM) and ferroelectric random access memory (FRAM) also face severe problems in scaling. In this circumstance, a renewed nonvolatile memory concept called resistance-switching random access memory (RRAM), which is based on resistance change modulated by electrical stimulus, has recently inspired scientific and commercial interests due to its high operation speed, high scalability, and multibit storage potential. 1-3 The reading of resistance states is nondestructive, and the memory devices can be operated without transistors in every cell, 4,5 thus making a cross-bar structure feasible. A large variety of solid-state materials have been found to show these resistive switching characteristics, including solid electrolytes such as GeSe and Ag 2 S, 5 perovskites such as SrZrO 3 and Pr 0.7 Ca 0.3 MnO 3 , 3,6 binary transition metal oxides such as NiO, TiO 2 , and ZnO, 7,8 and amorphous silicon (R-Si) as well as Si/R-Si core/shell nanowires. 2,9-11 Among them, binary transition metal oxides have simple compositions and exhibit resistive switching effects in polycrystalline states, in which case the require- ments for deposition techniques, temperatures, and substrates are minimized. It is therefore of interest to investigate the possibility of fabricating a high-performance resistive memory based on binary transition metal oxides by conventional industrialized techniques at low temperatures, which holds potential for industrialization and three-dimensional (3D) stacking. Here, we demonstrate the above-mentioned feasibility by developing a new kind of RRAM device consisting of Ag/ ZnO:Mn/Pt with ultrafast programming speed of 5 ns, an ultrahigh R OFF /R ON ratio of 10 7 , long retention time of more than 10 7 s, good endurance, and high reliability at elevated temperatures. The device preparation was completely ac- complished by a simple magnetron sputtering method at * Corresponding author, panf@mail.tsinghua.edu.cn. † Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University. ‡ Laboratory of Nano-fabrication and Novel Devices Integrated Technol- ogy, Institute of Microelectronics, Chinese Academy of Sciences. NANO LETTERS 2009 Vol. 9, No. 4 1636-1643 10.1021/nl900006g CCC: $40.75  2009 American Chemical Society Published on Web 03/09/2009