Thickness-induced structural phase transformation of layered gallium telluride
Thickness-induced structural phase transformation of layered gallium telluride
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层状碲化镓的厚度诱导结构相变
DOI：
10.1039/c6cp01963c
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发表时间：
2016
影响因子：
3.3
通讯作者：
Jie W.
中科院分区：
文献类型：
--
作者：
Zhao Q.;Wang T.;Miao Y.;Ma F.;Xie Y.;Ma X.;Gu Y.;Li J.;He J.;Chen B.;Xi S.;Xu L.;Zhen H.;Yin Z.;Li J.;Ren J.;Jie W.
二维材料与厚度相关的电子态和物理性质表明其在电子和光电器件中具有巨大的潜在应用。然而，超薄材料中增强的表面效应可能会显着影响结构稳定性以及器件可靠性。在这里，我们报告了碲化镓（GaTe）的自发相变，这种相变是在块体剥落成几层时发生的。透射电子显微镜（TEM）结果表明结构从单斜结构变为六方结构。拉曼光谱表明结构转变的临界厚度。第一原理计算和热力学分析表明，表面能和层间相互作用在减薄过程中竞争主导结构稳定性。提出了从单斜晶系（m）到四方晶系（T），然后从四方晶系到六方晶系（h）的两阶段转变过程来理解相变。结果证明了层间相互作用在结构稳定性中的关键作用，这为器件应用提供了相工程策略。
The thickness-dependent electronic states and physical properties of two-dimensional materials suggest great potential applications in electronic and optoelectronic devices. However, the enhanced surface effect in ultra-thin materials might significantly influence the structural stability, as well as the device reliability. Here, we report a spontaneous phase transformation of gallium telluride (GaTe) that occurred when the bulk was exfoliated to a few layers. Transmission electron microscopy (TEM) results indicate a structural variation from a monoclinic to a hexagonal structure. Raman spectra suggest a critical thickness for the structural transformation. First-principle calculations and thermodynamic analysis show that the surface energy and the interlayer interaction compete to dominate structural stability in the thinning process. A two-stage transformation process from monoclinic (m) to tetragonal (T) and then from tetragonal to hexagonal (h) is proposed to understand the phase transformation. The results demonstrate the crucial role of interlayer interactions in the structural stability, which provides a phase engineering strategy for device applications.