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arXiv 1608.04031cond-mat.mes-hallcond-mat.mtrl-sci
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原子薄MoSe2和WSe2中激子和三电子动力学:局域化效应

Exciton and trion dynamics in atomically thin MoSe2 and WSe2: effect of localization

D. Schmidt, T. Godde, J. Schmutzler, M. Aßmann, J. Debus, F. Withers, E. M. Alexeev, O. Del Pozo-Zamudio, O. V. Skrypka, K. S. Novoselov, M. Bayer, A. I. Tartakovskii

摘要:

本文详细研究了自然掺杂的MoSe_2和WSe_2单原子层在上述带隙激光激发下激子和三电子动力学随温度的变化。通过结合时间积分和时间分辨的光致发光(PL)光谱,我们显示了激子和trion本地化的重要性,在这两种材料在低温下。我们还揭示了在更高的温度下,激子和trion的热能超过典型的本地化能量的离域激子复合物的过渡。这是伴随着强烈的变化,PL包括抑制的trion PL和减少的trion PL寿命,以及显着的变化中性激子的PL强度的温度依赖性和外观的一个显着的缓慢PL衰减组件。在这里研究的MoSe 2和WSe 2中,观察到发生这种强烈变化的温度分别在100和200 K左右,与它们在T~ 10 K时8和20 meV的非均匀PL线宽一致。所观察到的行为是MoSe 2和WSe 2中亮激子和暗激子的特定能量排序、样品掺杂、trion和激子本地化以及各种温度依赖性非辐射过程的影响之间复杂相互作用的结果。

英文摘要:

We present a detailed investigation of the exciton and trion dynamics in naturally doped MoSe2 and WSe2 single atomic layers as a function of temperature in the range 10-300K under above band-gap laser excitation. By combining time-integrated and time-resolved photoluminescence (PL) spectroscopy we show the importance of exciton and trion localization in both materials at low temperatures. We also reveal the transition to delocalized exciton complexes at higher temperatures where the exciton and trion thermal energy exceeds the typical localization energy. This is accompanied with strong changes in PL including suppression of the trion PL and decrease of the trion PL life-time, as well as significant changes for neutral excitons in the temperature dependence of the PL intensity and appearance of a pronounced slow PL decay component. In MoSe2 and WSe2 studied here, the temperatures where such strong changes occur are observed at around 100 and 200 K, respectively, in agreement with their inhomogeneous PL linewidth of 8 and 20 meV at T~10K. The observed behavior is a result of a complex interplay between influences of the specific energy ordering of bright and dark excitons in MoSe2 and WSe2, sample doping, trion and exciton localization and various temperature-dependent non-radiative processes.

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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