Direct Observation of Metal-Insulator Transition in Single-Crystalline Germanium Telluride Nanowire Memory Devices Prior to Amorphization
Direct Observation of Metal-Insulator Transition in Single-Crystalline Germanium Telluride Nanowire Memory Devices Prior to Amorphization
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DOI：
10.1021/nl5007036
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发表时间：
2014-04-01
期刊：
影响因子：
10.8
通讯作者：
Agarwal, Ritesh
中科院分区：
文献类型：
--
作者：
Nukala, Pavan;Agarwal, Rahul;Agarwal, Ritesh
结构缺陷及其动力学在控制低功耗非易失性存储器件中使用的相变材料（PCM）的行为方面发挥着重要作用。然而，不太知道的影响，无序的结晶PCM的电子性质之前，结构相变。在这里，我们表明，施加电压脉冲单晶碲化锗纳米线存储器件引入位错和反相界（APB）的形式的结构紊乱。APB的动态演化和堆积增加了纳米线局部区域的无序，这使其从金属电子转变为脏金属再到绝缘体，同时仍然保持单晶长程有序。我们还观察到，接近这种金属-绝缘体转变，需要精确控制施加的电压，以创建一个绝缘状态，否则系统最终在一个更无序的非晶相，这表明在结构相变过程中的电子不稳定性的作用。
Structural defects and their dynamics play an important role in controlling the behavior of phase-change materials (PCM) used in low-power nonvolatile memory devices. However, not much is known about the influence of disorder on the electronic properties of crystalline PCM prior to a structural phase-change. Here, we show that the application of voltage pulses to single-crystalline GeTe nanowire memory devices introduces structural disorder in the form of dislocations and antiphase boundaries (APB). The dynamic evolution and pile-up of APBs increases disorder at a local region of the nanowire, which electronically transforms it from a metal to a dirty metal to an insulator, while still retaining single-crystalline long-range order. We also observe that close to this metal-insulator transition, precise control over the applied voltage is required to create an insulating state; otherwise the system ends up in a more disordered amorphous phase suggesting the role of electronic instabilities during the structural phase-change.