Abstract The unique surface edge states make topological insulators a primary focus among different applications. In this article, we synthesized a large single crystal of Niobium (Nb)-doped Bi2Se3 topological insulator (TI) with a formula Nb0·25Bi2Se3. The single crystal has characterized by using various techniques such as Powder X-ray Diffractometer (PXRD), DC magnetization measurements, Raman, and Ultrafast transient absorption spectroscopy (TRUS). There are (00l) reflections in the PXRD, and Superconductivity ingrown crystal is evident from clearly visible diamagnetic transition at 2.5 K in both FC and ZFC measurements. The Raman spectroscopy is used to find the different vibrational modes in the sample. Further, the sample is excited by a pump of 1.90 eV, and a kinetic decay profile at 1.38 eV is considered for terahertz analysis. The differential decay profile has different vibrations, and these oscillations have analyzed in terms of terahertz. This article not only provides evidence of terahertz generation in Nb-doped sample along with undoped sample but also show that the dopant atom changes the dynamics of charge carriers and thereby the shift in the Terahertz frequency response. In conclusion, a suitable dopant can be used as a processor for the tunability of terahertz frequency in TI.

中文翻译：

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拓扑绝缘体中的金属掺杂 - 太赫兹可调产生的关键

摘要 独特的表面边缘状态使拓扑绝缘体成为不同应用的主要焦点。在本文中，我们合成了一个大的铌 (Nb) 掺杂 Bi2Se3 拓扑绝缘体 (TI) 单晶，分子式为 Nb0·25Bi2Se3。单晶已通过使用各种技术表征，例如粉末 X 射线衍射仪 (PXRD)、直流磁化测量、拉曼和超快瞬态吸收光谱 (TRUS)。PXRD 中有 (00l) 反射，从 FC 和 ZFC 测量中 2.5 K 处清晰可见的抗磁性转变可以看出超导向内生长晶体。拉曼光谱用于发现样品中的不同振动模式。此外，样品由 1.90 eV 的泵激发，并考虑 1.38 eV 的动力学衰减曲线用于太赫兹分析。差分衰减曲线具有不同的振动，这些振动以太赫兹为单位进行了分析。本文不仅提供了 Nb 掺杂样品和未掺杂样品中太赫兹产生的证据，而且表明掺杂原子改变了电荷载流子的动力学，从而改变了太赫兹频率响应的偏移。总之，合适的掺杂剂可以用作 TI 中太赫兹频率可调的处理器。