Thermal conductivity of rutile germanium dioxide
Thermal conductivity of rutile germanium dioxide
复制标题
金红石型二氧化锗的导热性
DOI：
10.1063/5.0011358
复制
发表时间：
2020-09
影响因子：
4
通讯作者：
S. Chae;K. Mengle;R. Lu;A. Olvera;N. Sanders;J. Lee;P. Poudeu;J. Heron;E. Kioupakis
中科院分区：
文献类型：
--
作者：
S. Chae;K. Mengle;R. Lu;A. Olvera;N. Sanders;J. Lee;P. Poudeu;J. Heron;E. Kioupakis
功率电子器件寻求通过利用具有宽带隙、高载流子迁移率和高热导率的材料来改善器件的功率转换。β-Ga 2 O3由于其4.5 eV的宽带隙，在高压电子器件研究中受到了广泛关注。然而，它的低对称性晶体结构导致热传导效率低下。金红石型氧化锗（r-GeO 2）已被确定为一种替代的超宽带隙（4.68 eV）半导体，具有预测的高电子迁移率和双极掺杂性;然而，其热导率是未知的。在这里，我们表征的r-GeO 2的热导率作为温度的函数的第一性原理计算，实验合成，和热表征。计算预测r-GeO 2在300 K时的各向异性声子限制热导率沿a方向为37 W m−1 K−1沿着，沿c方向为58 W m−1 K−1沿着，其中声子限制热导率主要通过声学模式发生。在实验上，我们测量到热压的多晶r-GeO 2颗粒在300 K时的值为51 W m−1 K−1。测量值接近我们的方向平均的理论值，和温度的依赖性的Δ 1/T也与我们的理论预测一致，表明在我们的r-GeO 2样品在室温及以上的热输运是由声子散射。我们的研究结果表明，高对称性UWBG材料，如r-GeO 2，可能是高效电力电子的关键。
Power electronics seek to improve power conversion of devices by utilizing materials with a wide bandgap, high carrier mobility, and high thermal conductivity. Due to its wide bandgap of 4.5 eV, β-Ga2O3 has received much attention for high-voltage electronic device research. However, it suffers from inefficient thermal conduction that originates from its low-symmetry crystal structure. Rutile germanium oxide (r-GeO2) has been identified as an alternative ultra-wide-bandgap (4.68 eV) semiconductor with a predicted high electron mobility and ambipolar dopability; however, its thermal conductivity is unknown. Here, we characterize the thermal conductivity of r-GeO2 as a function of temperature by first-principles calculations, experimental synthesis, and thermal characterization. The calculations predict an anisotropic phonon-limited thermal conductivity for r-GeO2 of 37 W m−1 K−1 along the a direction and 58 W m−1 K−1 along the c direction at 300 K where the phonon-limited thermal conductivity predominantly occurs via the acoustic modes. Experimentally, we measured a value of 51 W m−1 K−1 at 300 K for hot-pressed, polycrystalline r-GeO2 pellets. The measured value is close to our directionally averaged theoretical value, and the temperature dependence of ∼1/T is also consistent with our theory prediction, indicating that thermal transport in our r-GeO2 samples at room temperature and above is governed by phonon scattering. Our results reveal that high-symmetry UWBG materials, such as r-GeO2, may be the key to efficient power electronics.