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arXiv 2408.15469cond-mat.mtrl-scicond-mat.mes-hall
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通过高温物理气相沉积对单层MoSe$_2$中激子的双轴应变调控

Biaxial strain tuning of excitons in monolayer MoSe$_2$ by high-temperature physical vapor deposition

S. Patel, T. Faltermeier, S. Puri, R. Rodriguez, K. Reynolds, S. Davari, H. O. H. Churchill, N. J. Borys, H. Nakamura

AI总结:

本文利用高温物理气相沉积在Si₃N₄和SiO₂衬底上对单层MoSe₂施加双轴拉伸应变,实现了103 meV/%的激子调控速率,为过渡金属二硫化物中最高值,并通过光谱表征揭示了应变分布特性,为光电子器件应变工程提供了有效途径。

摘要:

我们展示了利用高温物理气相沉积(PVD)对单层MoSe$_2$中激子发射的应变调控。使用两种非晶衬底Si$_{3}$N$_{4}$和SiO$_{2}$,提供了两个设定点,以诱导由单层与衬底之间的热膨胀失配所决定的不同程度的双轴拉伸应变。通过光致发光(PL)测得$A$激子跃迁能量的调控速率为103 meV/\\%,这是在过渡金属二硫化物中通过双轴应变实现的最高值。拉伸应变的双轴特性通过偏振分辨二次谐波产生得到确认,其揭示了单层未受扰动的面内三重对称性。此外,在拉曼光谱中识别出$A_\mathrm{1g}$面外晶格振动的软化,而该软化对于单轴应变而言已知是不显著的。同时,我们的PVD单层的PL成像表明:(i)单畴岛内部相较于边缘产生更大的应变;(ii)诱导应变的大小不存在岛尺寸依赖性。我们的结果展示了一条利用生长衬底进行激子应变工程的有效路径,这作为未来光电子应用的构建模块具有巨大前景。

英文摘要:

We present strain tuning of excitonic emission in monolayer MoSe$_2$ by using a high-temperature physical vapor deposition (PVD). The use of two amorphous substrates, Si$_{3}$N$_{4}$ and SiO$_{2}$, provides two setpoints to induce distinct amounts of \textit{biaxial} tensile strain determined by a thermal expansion mismatch between the monolayer and the substrate. The tuning rate of the $A$-exciton transition energy is found to be 103 meV/\% by photoluminescence (PL), which represents the highest value realized by biaxial strain in transition metal dichalcogenides. The biaxial nature of the tensile strain is confirmed by polarization-resolved second harmonic generation, which reveals unperturbed in-plane three-fold symmetry of the monolayer. Furthermore, a softening of $A_\mathrm{1g}$ out-of-plane lattice vibration is identified in the Raman spectroscopy, which is known to be insignificant for uniaxial strain. Concomitantly, PL mapping of our PVD monolayers demonstrates (i) larger strain occurs in the interior of the mono-domain islands compared to the edges and (ii) the absence of island-size dependence in the magnitude of induced strain. Our results demonstrate an effective path towards strain engineering of excitons by using growth substrates, which holds great promise as a building block for future optoelectronic applications.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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