Electrical and structural properties of binary Ga–Sb phase change memory alloys
Electrical and structural properties of binary Ga–Sb phase change memory alloys
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DOI：
10.1063/5.0096022
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发表时间：
2022-07
影响因子：
3.2
通讯作者：
Rubab Ume;H. Gong;V. Tokranov;M. Yakimov;Kevin Brew;G. Cohen;C. Lavoie;S. Schujman;Jing Liu;A. Frenkel;K. Beckmann;N. Cady;S. Oktyabrsky
中科院分区：
文献类型：
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作者：
Rubab Ume;H. Gong;V. Tokranov;M. Yakimov;Kevin Brew;G. Cohen;C. Lavoie;S. Schujman;Jing Liu;A. Frenkel;K. Beckmann;N. Cady;S. Oktyabrsky
研究了在超高真空条件下制备的用于模拟相变存储器（PCM）的Ga-Sb二元合金薄膜的材料特性。该合金的结晶发生在180-264 °C的温度范围内，活化能>2.5 eV，具体取决于成分。X射线衍射（XRD）的研究表明，结晶成两个阶段，Ga掺杂的A7锑和立方锌掺杂GaSb的相分离。同步辐射原位XRD分析表明，晶化到A7相伴随着Ga从晶粒向外扩散。这些合金的局部结构的X射线吸收精细结构研究表明，键长减少与稳定的配位数为4时，非晶到结晶相变。用Ga-Sb合金在直径为110 nm的TiN加热器上制作的蘑菇状电池结构在电脉冲下显示出电阻比>100的相变材料电阻开关行为。经过100次开关循环后，Ga-Sb电池的TEM和能量色散谱（EDS）研究表明，通过改变材料的晶粒尺寸以及A7相中的Ga含量，可以获得部分SET或中间电阻状态。提出了一种用于模拟单元性能的可逆组成控制的机制。这些结果表明，无Te的Ga-Sb二元合金是模拟PCM应用的潜在候选者。
Material properties of Ga–Sb binary alloy thin films deposited under ultra-high vacuum conditions were studied for analog phase change memory (PCM) applications. Crystallization of this alloy was shown to occur in the temperature range of 180–264 °C, with activation energy >2.5 eV depending on the composition. X-ray diffraction (XRD) studies showed phase separation upon crystallization into two phases, Ga-doped A7 antimony and cubic zinc-blende GaSb. Synchrotron in situ XRD analysis revealed that crystallization into the A7 phase is accompanied by Ga out-diffusion from the grains. X-ray absorption fine structure studies of the local structure of these alloys demonstrated a bond length decrease with a stable coordination number of 4 upon amorphous-to-crystalline phase transformation. Mushroom cell structures built with Ga–Sb alloys on ø110 nm TiN heater show a phase change material resistance switching behavior with resistance ratio >100 under electrical pulse measurements. TEM and Energy Dispersive Spectroscopy (EDS) studies of the Ga–Sb cells after ∼100 switching cycles revealed that partial SET or intermediate resistance states are attained by the variation of the grain size of the material as well as the Ga content in the A7 phase. A mechanism for a reversible composition control is proposed for analog cell performance. These results indicate that Te-free Ga–Sb binary alloys are potential candidates for analog PCM applications.