Composition graded nanowires (NWs) have attracted increasing research interest in the application of optoelectronic devices, due to their graded bandgaps caused by the changing composition. However, the thermal transport property of composition graded NWs is not clear, which is critical for their potential applications in electronics and thermoelectrics. In this Letter taking SiGe NW as an example, we explore the thermal transport property of composition graded NWs. Molecular dynamics simulations reveal that the thermal conductivities (κ) of the composition graded SiGe NWs can be reduced up to 57% compared with that of the corresponding SiGe NW with abrupt interfaces. The κ reduction stems from the shortening of phonon mean free paths due to the inhomogeneous composition distributions. The phonon wave packet propagation analysis reveals that the composition gradient can reflect more than 70% of the wave packet energy, and phonon localization is observed in the composition graded region. Our findings suggest a promising prospect of composition graded NWs in the use of thermoelectrics and high temperature coatings, where low thermal conductivity is expected.Composition graded nanowires (NWs) have attracted increasing research interest in the application of optoelectronic devices, due to their graded bandgaps caused by the changing composition. However, the thermal transport property of composition graded NWs is not clear, which is critical for their potential applications in electronics and thermoelectrics. In this Letter taking SiGe NW as an example, we explore the thermal transport property of composition graded NWs. Molecular dynamics simulations reveal that the thermal conductivities (κ) of the composition graded SiGe NWs can be reduced up to 57% compared with that of the corresponding SiGe NW with abrupt interfaces. The κ reduction stems from the shortening of phonon mean free paths due to the inhomogeneous composition distributions. The phonon wave packet propagation analysis reveals that the composition gradient can reflect more than 70% of the wave packet energy, and phonon localization is observed in the composition graded region. Our findings sugge...

中文翻译：

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成分梯度 SiGe 纳米线中的热传输受阻

成分梯度纳米线（NWs）由于成分变化引起的梯度带隙，在光电器件的应用中引起了越来越多的研究兴趣。然而，成分分级 NW 的热传输特性尚不清楚，这对其在电子和热电领域的潜在应用至关重要。在这封信中，以 SiGe NW 为例，我们探讨了成分分级 NW 的热传输特性。分子动力学模拟表明，与具有突变界面的相应 SiGe NW 相比，成分梯度 SiGe NW 的热导率 (κ) 可降低高达 57%。κ 减少源于声子平均自由程由于不均匀的成分分布而缩短。声子波包传播分析表明，成分梯度可以反射70%以上的波包能量，在成分梯度区域观察到声子定位。我们的研究结果表明，成分梯度纳米线在热电材料和高温涂层的使用中具有广阔的前景，其中预期热导率较低。 成分梯度纳米线（NWs）由于其梯度带隙而在光电器件的应用中引起了越来越多的研究兴趣成分变化引起的。然而，成分分级 NW 的热传输特性尚不清楚，这对其在电子和热电领域的潜在应用至关重要。在这封信中，以 SiGe NW 为例，我们探讨了成分分级 NW 的热传输特性。分子动力学模拟表明，与具有突变界面的相应 SiGe NW 相比，成分梯度 SiGe NW 的热导率 (κ) 可降低高达 57%。κ 减少源于声子平均自由程由于不均匀的成分分布而缩短。声子波包传播分析表明，成分梯度可以反射70%以上的波包能量，在成分梯度区域观察到声子定位。我们的研究结果表明... κ 减少源于声子平均自由程由于不均匀的成分分布而缩短。声子波包传播分析表明，成分梯度可以反射70%以上的波包能量，在成分梯度区域观察到声子定位。我们的研究结果表明... κ 减少源于声子平均自由程由于不均匀的成分分布而缩短。声子波包传播分析表明，成分梯度可以反射70%以上的波包能量，在成分梯度区域观察到声子定位。我们的研究结果表明...