School of Materials Science and Engineering and ‡Center for Integrated Computational Materials Engineering, International Research Institute for Multidisciplinary Science, Beihang University , Beijing 100191, China.
ACS Appl Mater Interfaces. 2016 Oct 5;8(39):26126-26134. doi: 10.1021/acsami.6b08700. Epub 2016 Sep 22.
SbTe exhibits outstanding performance among the candidate materials for phase-change memory; nevertheless, its low electrical resistivity and thermal stability hinder its practical application. Hence, numerous studies have been carried out to search suitable dopants to improve the performance; however, the explored dopants always cause phase separation and thus drastically reduce the reliability of phase-change memory. In this work, on the basis of ab initio calculations, we have identified yttrium (Y) as an optimal dopant for SbTe, which overcomes the phase separation problem and significantly increases the resistivity of crystalline state by at least double that of SbTe. The good phase stability of crystalline Y-doped SbTe (YST) is attributed to the same crystal structure between YTe and SbTe as well as their tiny lattice mismatch of only ∼1.1%. The significant increase in resistivity of c-YST is understood by our findings that Y can dramatically increase the carrier's effective mass by regulating the band structure and can also reduce the intrinsic carrier density by suppressing the formation of Sb antisite defects. Y doping can also improve the thermal stability of amorphous YST based on our ab initio molecular dynamics simulations, which is attributed to the stronger interactions between Y and Te than that of Sb and Te.
碲化锑在相变存储器的候选材料中表现出色；然而，其低电阻率和热稳定性阻碍了其实际应用。因此，已经进行了大量研究来寻找合适的掺杂剂来改善性能；然而，所探索的掺杂剂总是会导致相分离，从而极大地降低相变存储器的可靠性。在这项工作中，我们基于第一性原理计算，确定了钇（Y）是碲化锑的最佳掺杂剂，它克服了相分离问题，并使晶态电阻率至少提高一倍，晶态 Y 掺杂 SbTe（YST）的良好相稳定性归因于 YTe 和 SbTe 之间相同的晶体结构以及它们仅约 1.1%的微小晶格失配。通过我们的发现，可以理解 c-YST 电阻率的显著增加，即 Y 可以通过调节能带结构极大地增加载流子的有效质量，并且还可以通过抑制 Sb 反位缺陷的形成来降低本征载流子密度。基于我们的第一性原理分子动力学模拟，Y 掺杂还可以提高非晶态 YST 的热稳定性，这归因于 Y 和 Te 之间的相互作用强于 Sb 和 Te。
