发表机构
Center for Quantum Information Physics, New York University; Pacific Northwest National Laboratory（纽约大学量子信息物理中心; 太平洋西北国家实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究比较了InP上Nb超导谐振器的三种衬底制备方法，发现硫钝化能更有效抑制界面氧并改善材料性能，但微波响应相当，表明器件不受埋层界面介电损耗限制。
AI 中文摘要
衬底表面制备是电子器件制造中的关键步骤。在III-V族半导体平台（例如用于高电子迁移率晶体管（HEMT）和激光器的平台）中，去除原生衬底氧化物极为重要，若去除不当将对器件最终性能产生负面影响。然而，在与量子信息应用相关的混合超导体-半导体（S-Sm）系统中，衬底制备的影响仍知之甚少。本研究比较了在InP上溅射沉积Nb薄膜的三种表面制备方法：（i）无刻意氧化物去除（对照组），（ii）原位Ar+离子铣削，以及（iii）硫钝化。原位Ar+离子铣削降低了金属-衬底（MS）界面处的氧浓度，但也使InP表面粗糙化，增加了Nb-InP界面的有效厚度，并通过Nb薄膜中的扩展缺陷促进了氧的掺入。硫钝化更有效地抑制了界面氧，同时保持了更尖锐、更平滑的埋层界面。与Ar+离子铣削样品相比，硫钝化还使Nb薄膜具有更高的超导转变温度和更少的结构损伤。尽管有这些材料上的改进，三种制备方法的微波响应相当。在单光子功率下，对照组谐振器的最高内品质因子Qi约为1.30×10^5（130k），硫钝化谐振器为9.7×10^4（97k），Ar+离子铣削谐振器为8.4×10^4（84k）。这些结果表明，当前器件的主要限制因素并非埋层Nb-InP界面的介电损耗。
英文摘要
Substrate surface preparation is a key step in the fabrication of electronic devices. In III--V semiconductor platforms, e.g. used in HEMTs and lasers, removal of the native substrate oxide is extremely important, where improper removal will negatively affect end-of-line device performance. However, the impact of substrate preparation in hybrid superconductor--semiconductor (S--Sm) systems relevant to quantum information applications remains poorly understood. This study compares three surface preparations for the deposition of sputtered Nb films on InP: (i) no intentional oxide removal (control), (ii) \textit{in-situ} $\mathrm{Ar}^{+}$ milling, and (iii) S-passivation. \textit{In-situ} $\mathrm{Ar}^{+}$ milling reduces the O concentration at the metal--substrate (MS) interface, but also roughens the InP surface, increasing the effective thickness of the Nb--InP interface and promoting O incorporation through extended defects in the Nb film. S-passivation suppresses interfacial O more effectively while preserving a sharper and smoother buried interface. It also yields Nb films with higher superconducting transition temperatures and less structural damage than the $\mathrm{Ar}^{+}$-milled samples. Despite these materials improvements, the microwave response is comparable across the three preparations. At single photon powers, the highest internal quality factors, $Q_i$, are approximately $1.30\times10^{5}$ ($130\mathrm{k}$) for the control resonators, $9.7\times10^{4}$ ($97\mathrm{k}$) for the S-passivated resonators, and $8.4\times10^{4}$ ($84\mathrm{k}$) for the $\mathrm{Ar}^{+}$-milled resonators. These results suggest that the present devices are not primarily limited by dielectric loss at the buried Nb--InP interface.
