Gupta Jay Deep, Jangra Priyanka, Majee Bishnu Pada, Mishra Ashish Kumar
School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University) Varanasi-221005 India
Nanoscale Adv. 2023 Apr 12;5(10):2756-2766. doi: 10.1039/d3na00164d. eCollection 2023 May 16.
Thermal transport and exciton dynamics of semiconducting transition metal dichalcogenides (TMDCs) play an immense role in next-generation electronic, photonic, and thermoelectric devices. In this work, we synthesize distinct morphologies (snow-like and hexagonal) of a trilayer MoSe film over the SiO/Si substrate the chemical vapor deposition (CVD) method and investigated their morphological dependent exciton dynamics and thermal transport behaviour for the first time to the best of our knowledge. Firstly, we studied the role of spin-orbit and interlayer couplings both theoretically as well as experimentally first-principles density functional theory and photoluminescence study, respectively. Further, we demonstrate morphological dependent thermal sensitive exciton response at low temperatures (93-300 K), showing more dominant defect-bound excitons () in snow-like MoSe compared to hexagonal morphology. We also examined the morphological-dependent phonon confinement and thermal transport behaviour using the optothermal Raman spectroscopy technique. To provide insights into the nonlinear temperature-dependent phonon anharmonicity, a semi-quantitative model comprising volume and temperature effects was used, divulging the dominance of three-phonon (four-phonon) scattering processes for thermal transport in hexagonal (snow-like) MoSe. The morphological impact on thermal conductivity () of MoSe has also been examined here by performing the optothermal Raman spectroscopy, showing ∼ 36 ± 6 W m K for snow-like and ∼41 ± 7 W m K for hexagonal MoSe. Our research will contribute to the understanding of thermal transport behaviour in different morphologies of semiconducting MoSe, finding suitability for next-generation optoelectronic devices.
半导体过渡金属二硫属化物（TMDCs）的热输运和激子动力学在下一代电子、光子和热电器件中起着至关重要的作用。在这项工作中，我们通过化学气相沉积（CVD）方法在SiO/Si衬底上合成了具有不同形貌（雪状和六方）的三层MoSe薄膜，并据我们所知首次研究了它们基于形貌的激子动力学和热输运行为。首先，我们分别从理论和实验上研究了自旋轨道和层间耦合的作用，即分别采用第一性原理密度泛函理论和光致发光研究。此外，我们展示了在低温（93 - 300 K）下基于形貌的热敏激子响应，表明与六方形貌相比，雪状MoSe中缺陷束缚激子（）更为占主导。我们还使用光热拉曼光谱技术研究了基于形貌的声子限制和热输运行为。为了深入了解与温度相关的非线性声子非谐性，我们使用了一个包含体积和温度效应的半定量模型，揭示了六方（雪状）MoSe中热输运的三声子（四声子）散射过程的主导地位。在此，我们还通过光热拉曼光谱研究了形貌对MoSe热导率（）的影响，雪状MoSe的热导率约为36 ± 6 W m K，六方MoSe的热导率约为41 ± 7 W m K。我们的研究将有助于理解半导体MoSe不同形貌中的热输运行为，为下一代光电器件找到适用性。
