Temperature Dependence of Electrical Properties of NiO Thin Films for Resistive Random Access Memory
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1071-F08-08
Temperature Dependence of Electrical Properties of NiO Thin Films for Resistive Random Access Memory Ryota Suzuki1, Jun Suda1, and Tsunenobu Kimoto1,2 1 Department of Electronic Science and Engineering, Kyoto University, Kyotodaigaku-katsura, Nisikyo, Kyoto, 615-8510, Japan 2 Photonics and Electronics Science and Engineering Center (PESEC), Kyoto University, Kyotodaigaku-katsura, Nishikyo, Kyoto, 615-8510, Japan ABSTRACT Temperature dependence of electrical properties in NiO thin films for ReRAM applications has been investigated. I-V measurements have been carried out in the temperature range from 100K to 523K. The resistance in the high resistance state (HRS) is almost independent of temperature below 250K, whereas it decreases with an activation energy of 300 meV above 250K. Hopping conduction and band conduction may be dominant in the low- and high-temperature range, respectively. Admittance spectroscopy on the NiO/n+-Si structure reveals the existence of a high density of traps, which may contribute to the conduction in HRS. In the low resistance state (LRS), however, the resistance slightly increased in the whole temperature range and the trend is similar to that of metallic Ni film, indicating the metallic Ni defects is related to the conduction in LRS. The Pt/NiO/Pt structure demonstrated stable resistance switching even at temperature as high as 250ºC or higher. Since other competitive nonvolatile memories will face severe difficulty in high-temperature operation, the present ReRAM shows promise for high-temperature application. INTRODUCTION In recent years, the resistance switching behavior of binary transition metal oxides, such as NiO [1], TiO2 [2], has attracted much attention, owing to their potential for new-generation nonvolatile memory, Resistive Random Access Memory (ReRAM). ReRAM has advantages of miniaturization and low-power operation in comparison with other nonvolatile memories. ReRAM has another advantage of its compatibility with conventional complementary-metaloxide-semiconductor (CMOS) technologies. However, before pushing ReRAM to industrial application, one must resolve a number of issues, including designing resistance switching characteristics and device structure. Toward this goal, it is essential to elucidate the resistance switching mechanism of the material. Since the early 1960s, the resistance switching behavior of various transition metal oxides has been investigated [3]. These materials have two resistance states of low resistance state (LRS) and high resistance state (HRS) by applying external voltages. To explain the resistance switching phenomena, various models, such as trap charging/discharging, thermallyinduced chemical reaction and Mott transition model have been proposed [2, 4-5]. However, details of the physical origins of resistance switching behavior have not been clarified yet. It is important to establish the electrical conduction mechanism of resistance switching materials in order to find a clue for the resistance switching mechanism. Although it is
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