分子束外延沉积的高ScN含量ScAlN的强色散介电特性
Strongly dispersive dielectric properties of high-ScN-fraction ScAlN deposited by molecular beam epitaxy
AI总结：
该研究系统表征了MBE生长的高ScN含量ScAlN薄膜的介电特性，发现其介电常数随ScN含量和频率显著变化，并与溅射样品形成对比，揭示了沉积方法对材料介电行为的根本影响。
摘要：
我们全面研究了利用分子束外延（MBE）生长的高ScN含量ScAlN薄膜的介电特性，包括复介电常数、损耗和漏电流。对高ScN含量（30%-40% ScN含量）样品在20 Hz至10 GHz范围内进行了介电谱测量。我们发现实介电常数ε'随ScN含量增加而显著增大，这一趋势得到了密度泛函理论的证实。此外，ε'随频率和ScN含量增加表现出强色散特性，Sc0.4Al0.6N的ε'值随频率升高从150降至60。损耗、色散和直流漏电流也相应随ScN含量增加而增大。MBE ScAlN中的高ε'和强色散行为在具有相似ScN含量的溅射沉积ScAlN对照样品中未被观察到，这凸显了两种沉积方法所制备薄膜之间的根本差异。对MBE和溅射沉积样品进行了显微学和光谱学分析，以比较微观结构、合金成分和掺杂浓度。
英文摘要：
We present a comprehensive study of dielectric properties including complex permittivity, loss, and leakage of high-ScN-fraction ScAlN thin films grown using molecular beam epitaxy (MBE). Dielectric spectroscopy is carried out on high-ScN-fraction (30%-40% ScN fraction) samples from 20 Hz to 10 GHz. We find that real permittivity ε' increases significantly with increasing ScN fraction; a trend confirmed by density functional theory. Further, ε' is strongly dispersive with frequency and increasing ScN fraction, with values for Sc0.4Al0.6N varying from 150 down to 60 with increasing frequency. Loss, dispersion, and DC leakage current correspondingly increase with ScN fraction. The high ε' and strongly dispersive behavior in MBE ScAlN are not observed in a sputter-deposited ScAlN control with a similar ScN fraction, highlighting fundamental differences between films produced by the two deposition methods. Microscopy and spectroscopy analyses are carried out on MBE- and sputter-deposited samples to compare microstructure, alloy, and dopant concentration.
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