Cu2GeTe3 (CGT) is a promising phase change material for phase change random access memory (PCRAM) applications because of its high thermal stability in the amorphous phase and its capability to undergo rapid phase change. In this paper, the electrical conduction mechanism of a CGT memory device fabricated using W electrodes (W/CGT) was investigated using current–voltage (I–V) measurements and angle resolved hard x-ray photoelectron spectroscopy (AR-HAXPES). The I–V characteristics of the W/CGT memory device were found to display non-linear behavior in the RESET (amorphous) state, while linear behavior was observed in the SET (crystalline) state, indicating that the W/CGT memory device exhibited Schottky conduction in the RESET state, but Ohmic conduction in the SET state. The effective Schottky barrier height was found to increase linearly as the ideality factor decreased to unity with the ideal W/CGT Schottky barrier height in the RESET state estimated to be 0.33 eV, a value in good agreement with the directly measured Schottky barrier height of 0.35 eV between W and amorphous CGT by AR-HAXPES measurements. These results suggest that the interface between the metal electrode and the phase change material plays an important role in PCRAM devices, and its comprehensive understanding is necessary for future application development.

中文翻译：

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Cu2GeTe3相变存储器件中触点的重要性

Cu2GeTe3 (CGT) 是一种很有前途的相变材料，用于相变随机存取存储器 (PCRAM) 应用，因为它在非晶相中具有高热稳定性，并且能够进行快速相变。在本文中，使用电流-电压 (I-V) 测量和角分辨硬 X 射线光电子能谱 (AR-HAXPES) 研究了使用 W 电极 (W/CGT) 制造的 CGT 存储器件的导电机制。发现 W/CGT 存储器件的 I-V 特性在 RESET（非晶）状态下表现出非线性行为，而在 SET（结晶）状态下观察到线性行为，表明 W/CGT 存储器件表现出RESET 状态下肖特基导通，SET 状态下欧姆导通。发现有效肖特基势垒高度随着理想因子降低到一致而线性增加，复位状态下的理想 W/CGT 肖特基势垒高度估计为 0.33 eV，该值与直接测量的肖特基势垒高度 0.35 非常吻合通过 AR-HAXPES 测量，W 和非晶 CGT 之间的 eV。这些结果表明金属电极和相变材料之间的界面在 PCRAM 器件中起着重要作用，对其进行全面了解对于未来的应用开发是必要的。