Chemical substitution is a promising route for the exploration of a rich variety of doping- and/or disorder-dependent collective phenomena in low-dimensional quantum materials. Here we show that transition metal dichalcogenide alloys are ideal platforms to this purpose. In particular, we demonstrate the emergence of superconductivity in the otherwise metallic single-layer TaSe₂ by minute electron doping provided by substitutional W atoms. We investigate the temperature and magnetic field dependence of the superconducting state of Ta_1-δW_δSe₂ with electron doping (δ) using variable temperature (0.34–4.2 K) scanning tunneling spectroscopy (STS). We unveil the emergence of a superconducting dome spanning 0.003 < δ < 0.03 with a maximized critical temperature of 0.9 K, a significant increase from that of bulk TaSe₂ (T_C = 0.14 K). Superconductivity emerges from an increase of the density of states (DOS) as the Fermi surface approaches a van Hove singularity due to doping. Once the singularity is reached, however, the DOS decreases with δ, which gradually weakens the superconducting state, thus shaping the superconducting dome. Lastly, our doping-dependent measurements suggest the development of a Coulomb glass phase triggered by disorder due to W dopants.

化学取代是探索低维量子材料中丰富多样的掺杂和/或无序依赖性集体现象的有前途的途径。在这里，我们表明过渡金属二硫化物合金是实现此目的的理想平台。特别是，我们通过替代 W 原子提供的微小电子掺杂证明了在其他金属单层 TaSe _{2中超导性的出现。}我们研究了具有电子掺杂的 Ta _1-δ W _δ Se ₂超导态的温度和磁场依赖性( δ) 使用可变温度 (0.34–4.2 K) 扫描隧道光谱 (STS)。我们揭示了跨越 0.003 <  δ  < 0.03 的超导圆顶的出现，其最大临界温度为 0.9 K，比块状 TaSe ₂ ( T _C  = 0.14 K) 显着增加。当费米表面由于掺杂接近范霍夫奇点时，状态密度 (DOS) 的增加会产生超导性。然而，一旦达到奇点，DOS 随δ减小，这逐渐削弱超导状态，从而形成超导圆顶。最后，我们的掺杂相关测量表明，由于 W 掺杂剂引起的无序触发了库仑玻璃相的发展。