CaCu3Ti4O12 (CCTO)電阻轉換特性及電阻轉換機制之研究

Abstract

近來，各類新式非揮發性記憶受到廣泛的注意。其中，具有雙穩態電阻值之電阻式隨機存取記憶體，因其具有非揮發性、低功率、高密度及多狀態記憶位元等特性，而吸引了研究者們對此方面之興趣。因此，電阻式記憶體儼然成為下一世代非揮發性記憶體選擇之一。由於電阻式非揮發性記憶體的各項優越條件，使其非常有機會成為下一世代非揮發性記憶體之主流。但由於其電阻轉換機制目前尚不明朗，因此市面上遲遲未有其相關應用產品。在這篇論文中，採用CaCu3Ti4O12(CCTO)做為電阻轉態元件材料。探討退火溫度對CCTO電阻轉換特性之影響。並且藉由交流阻抗分析，探討其電阻轉換機制，並建立其電阻轉換之等效電路及物理模型。最後，探討電極材料對於其電阻轉換之影響。

Recently, many kinds of new nonvolatile memory manufactured from different materials have attracted great attention. The resistance random access memory (RRAM) which has bistable resistive switching character started to attract the research community’s interest again as a nonvolatile, low power, high density, and multi-bit operating memory. Accordingly, RRAM has been proposed to be one candidate of next generation nonvolatile memories. In this study, the bistable resistance switching characteristics of CaCu3Ti4O12 (CCTO) films prepared by sol-gel method and annealed at various temperatures are investigated. The correlation between resistance switching behaviors and crystallinity of the films are also explored. The resistance switching mechanisms are investigated by the impedance spectroscopy technique. The equivalent circuit and physical model for resistance switching are proposed. Finally, the effects of the electrode materials are also examined.