Titanium nitride (TiN) film is a remarkable material for a variety of applications ranging from superhard coating to superconducting quantum devices, which can be easily oxidized when it works in the atmosphere. However, the study of its oxidation effect on the crystal and electronic structures of epitaxial TiN films is rare as yet. Here, we coherently synthesize TiN epitaxial films on MgO single crystal substrates via reactive magnetron sputtering and, then, dope oxygen into these films via a controllable oxidation process. The crystal and electronic structures are characterized by high-resolution x-ray diffraction, x-ray photoelectron spectra, and Raman spectra. It is revealed that the crystal structure remains to be of the rocksalt type in these films even with heavy oxygen doping. The data of temperature-dependent electrical transport measurements indicate that the superconducting critical temperature (kinetic inductance) decreases (increases) from 4.6 K (0.672 pH/□) in the pristine TiN film to 3.4 K (1.13 pH/□) in the film with a maximum oxygen doping level. Our work provides a controllable way to tune the superconductivity of TiN films, which enables the flexibility to engineer the resultant performance of TiN-based superconducting quantum devices.

中文翻译：

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通过氧掺杂可调节外延TiN薄膜的超导性

氮化钛（TiN）膜是卓越的材料，可用于从超硬涂层到超导量子器件的各种应用，当它在大气中工作时，很容易被氧化。然而，对其外延TiN薄膜的晶体和电子结构的氧化作用的研究还很少。在这里，我们通过反应磁控溅射在MgO单晶衬底上相干合成TiN外延膜，然后通过可控的氧化过程将氧掺杂到这些膜中。晶体和电子结构的特征在于高分辨率x射线衍射，x射线光电子能谱和拉曼光谱。结果表明，即使掺杂大量氧，这些膜的晶体结构仍保持为岩盐型。随温度变化的电迁移测量数据表明，超导临界温度（动态电感）从原始TiN薄膜中的4.6 K（0.672 pH /□）降低（增加）到薄膜中的3.4 K（1.13 pH /□）。最大氧掺杂水平。我们的工作提供了一种可调节的方法来调节TiN薄膜的超导性，从而可以灵活地设计基于TiN的超导量子器件的最终性能。