Department of Materials Science, Graduate School of Engineering, Tohoku University , 6-6-11 Aoba-yama, Sendai 980-8579, Japan.
Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan.
ACS Appl Mater Interfaces. 2018 Jan 24;10(3):2725-2734. doi: 10.1021/acsami.7b16755. Epub 2018 Jan 10.
Phase-change random access memory (PCRAM) has attracted much attention for next-generation nonvolatile memory that can replace flash memory and can be used for storage-class memory. Generally, PCRAM relies on the change in the electrical resistance of a phase-change material between high-resistance amorphous (reset) and low-resistance crystalline (set) states. Herein, we present an inverse resistance change PCRAM with CrGeTe (CrGT) that shows a high-resistance crystalline reset state and a low-resistance amorphous set state. The inverse resistance change was found to be due to a drastic decrease in the carrier density upon crystallization, which causes a large increase in contact resistivity between CrGT and the electrode. The CrGT memory cell was demonstrated to show fast reversible resistance switching with a much lower operating energy for amorphization than a GeSbTe memory cell. This low operating energy in CrGT should be due to a small programmed amorphous volume, which can be realized by a high-resistance crystalline matrix and a dominant contact resistance. Simultaneously, CrGT can break the trade-off relationship between the crystallization temperature and operating speed.
相变随机存取存储器 (PCRAM) 作为下一代非易失性存储器，受到了极大的关注，它可以替代闪存，并可用于存储级内存。通常，PCRAM 依赖于相变材料的电阻在高电阻非晶态（重置）和低电阻晶态（设置）之间的变化。在此，我们提出了一种具有 CrGeTe（CrGT）的反向电阻变化 PCRAM，其表现出高电阻晶态重置状态和低电阻非晶态设置状态。发现反向电阻变化是由于结晶时载流子密度的急剧下降，导致 CrGT 与电极之间的接触电阻率大幅增加。CrGT 存储单元表现出快速可逆的电阻开关特性，其非晶化的工作能量远低于 GeSbTe 存储单元。CrGT 的低工作能量应该归因于小的编程非晶体积，这可以通过高电阻晶态矩阵和主导接触电阻来实现。同时，CrGT 可以打破结晶温度和工作速度之间的权衡关系。
