Fang Mengke, Liu Xiao, Liu Jinxin, Chen Yangbo, Su Yue, Wei Yuehua, Zhou Yuquan, Peng Gang, Cai Weiwei, Deng Chuyun, Zhang Xue-Ao
College of Physical Science and Technology, Xiamen University, Xiamen 361005, China.
College of Science, National University of Defense Technology, Changsha 410073, China.
Nanomaterials (Basel). 2023 Jun 7;13(12):1817. doi: 10.3390/nano13121817.
WTe, a low-symmetry transition metal dichalcogenide, has broad prospects in functional device applications due to its excellent physical properties. When WTe flake is integrated into practical device structures, its anisotropic thermal transport could be affected greatly by the substrate, which matters a lot to the energy efficiency and functional performance of the device. To investigate the effect of SiO/Si substrate, we carried out a comparative Raman thermometry study on a 50 nm-thick supported WTe flake (with κ = 62.17 W·m·K and κ = 32.93 W·m·K), and a suspended WTe flake of similar thickness (with κ = 4.45 W·m·K, κ = 4.10 W·m·K). The results show that the thermal anisotropy ratio of supported WTe flake (κ/κ ≈ 1.89) is about 1.7 times that of suspended WTe flake (κ/κ ≈ 1.09). Based on the low symmetry nature of the WTe structure, it is speculated that the factors contributing to thermal conductivity (mechanical properties and anisotropic low-frequency phonons) may have affected the thermal conductivity of WTe flake in an uneven manner when supported on a substrate. Our findings could contribute to the 2D anisotropy physics and thermal transport study of functional devices based on WTe and other low-symmetry materials, which helps solve the heat dissipation problem and optimize thermal/thermoelectric performance for practical electronic devices.
WTe₂是一种低对称性的过渡金属二硫属化物，因其优异的物理性能在功能器件应用方面具有广阔前景。当将WTe₂薄片集成到实际器件结构中时，其各向异性的热输运可能会受到衬底的极大影响，这对器件的能量效率和功能性能至关重要。为了研究SiO₂/Si衬底的影响，我们对一片50纳米厚的支撑WTe₂薄片（κₗ = 62.17 W·m⁻¹·K⁻¹，κₜ = 32.93 W·m⁻¹·K⁻¹）以及一片类似厚度的悬空WTe₂薄片（κₗ = 4.45 W·m⁻¹·K⁻¹，κₜ = 4.10 W·m⁻¹·K⁻¹）进行了对比拉曼热成像研究。结果表明，支撑WTe₂薄片的热各向异性比（κₗ/κₜ ≈ 1.89）约为悬空WTe₂薄片（κₗ/κₜ ≈ 1.09）的1.7倍。基于WTe₂结构的低对称性，推测导致热导率的因素（机械性能和各向异性低频声子）在支撑于衬底上时可能以不均匀的方式影响了WTe₂薄片的热导率。我们的研究结果有助于基于WTe₂和其他低对称性材料的功能器件的二维各向异性物理和热输运研究，这有助于解决散热问题并优化实际电子器件的热/热电性能。
