Effective heat dissipation is the bottleneck problem for the development and commercialization of GaN-based high-power electronic and photonic devices. To address this challenge and explore the underlying mechanism of phonon transportation across the GaN/AlN heterointerface, in this work, we formed three types of GaN/AlN heterostructures with distinctively different interfacial morphologies by annealing recrystallization approach. It is found that the interfacial thermal conductance (ITC) of GaN/AlN heterostructures can be remarkably improved by tailoring the interfacial crystal structure and phase morphology. Besides the commonly amorphous phase and ideal ordered wurtzite phase, we further found that AlN may present an additional stable rock salt phase at the interfacial region, and its significant effect on interfacial thermal transport has been observed. Using molecular dynamics simulation, we systematically investigated the effects of different GaN/AlN heterojunctions on the ITCs. Our results suggest that heat dissipation at the GaN/AlN interface is dominated by phonons scattered diffusely by the amorphous region at interfaces and the ITC can be significantly enhanced by recrystallizing the amorphous AlN to rock salt one. Furthermore, through phonon vibrational spectrum, we revealed that phonon modes dominate the energy transport across the interfaces of wurtzite AlN/GaN, amorphous AlN/GaN, and rock salt AlN/GaN are significantly different. Finally, we found the ITC increased with the temperature due to the enhanced inelastic phonon scattering and the presence of additional excited phonon modes at higher temperatures. The findings elucidated here provide a clearer insight into the effect of interfacial microstructures on the interfacial thermal resistance of GaN–substrate interface, which also provide a viable heat management strategy for the high-power GaN-based devices.

中文翻译：

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用于增强 GaN/AlN 异质结构中界面热导的界面工程

有效散热是GaN基大功率电子和光子器件开发和商业化的瓶颈问题。为了应对这一挑战并探索声子在 GaN/AlN 异质界面上传输的潜在机制，在这项工作中，我们通过退火再结晶方法形成了三种具有明显不同界面形态的 GaN/AlN 异质结构。研究发现，通过调整界面晶体结构和相形貌，可以显着提高 GaN/AlN 异质结构的界面热导 (ITC)。除了常见的无定形相和理想的有序纤锌矿相外，我们进一步发现 AlN 可能在界面区域呈现出额外的稳定岩盐相，并且已经观察到它对界面热传输的显着影响。使用分子动力学模拟，我们系统地研究了不同 GaN/AlN 异质结对 ITC 的影响。我们的结果表明，GaN/AlN 界面处的散热主要由界面处的非晶区域扩散散射的声子支配，并且可以通过将非晶 AlN 重结晶为岩盐来显着增强 ITC。此外，通过声子振动光谱，我们揭示了声子模式主导了纤锌矿 AlN/GaN、非晶 AlN/GaN 和岩盐 AlN/GaN 界面的能量传输，这些有显着不同。最后，我们发现由于增强的非弹性声子散射和在较高温度下存在额外的激发声子模式，ITC 随温度增加而增加。