We report transport measurements on Josephson junctions consisting of Bi₂Te₃ topological insulator (TI) thin films contacted by superconducting Nb electrodes. For a device with junction length L = 134 nm, the critical supercurrent I _c can be modulated by an electrical gate which tunes the carrier type and density of the TI film. I _c can reach a minimum when the TI is near the charge neutrality regime with the Fermi energy lying close to the Dirac point of the surface state. In the p-type regime the Josephson current can be well described by a short ballistic junction model. In the n-type regime the junction is ballistic at 0.7 K < T < 3.8 K while for T < 0.7 K the diffusive bulk modes emerge and contribute a larger I _c than the ballistic model. We attribute the lack of diffusive bulk modes in the p-type regime to the formation of p–n junctions. Our work provides new clues for search of Majorana zero mode in TI-based superconducting devices.

我们报告了对由超导 Nb 电极接触的 Bi ₂ Te ₃拓扑绝缘体 (TI) 薄膜组成的约瑟夫森结的传输测量。对于结长L = 134 nm的器件，临界超电流I _c可以通过调节 TI 薄膜的载流子类型和密度的电门进行调制。当 TI 接近电荷中性状态且费米能量接近表面态的狄拉克点时，I _c可以达到最小值。在 p 型状态下，约瑟夫森电流可以通过短弹道结模型很好地描述。在 n 型区域中，结在 0.7 K < T < 3.8 K 时是弹道的，而对于T < 0.7 K，扩散体模式出现并贡献比弹道模型更大的I _c。我们将 p 型区域中缺乏扩散体模式归因于 p-n 结的形成。我们的工作为在基于 TI 的超导器件中寻找马约拉纳零模式提供了新的线索。