Two-dimensional (2D) crystals have emerged as a class of materials with tunable carrier density¹. Carrier doping to 2D semiconductors can be used to modulate many-body interactions² and to explore novel composite particles. The Holstein polaron is a small composite particle of an electron that carries a cloud of self-induced lattice deformation (or phonons)^3,4,5, which has been proposed to play a key role in high-temperature superconductivity⁶ and carrier mobility in devices⁷. Here we report the discovery of Holstein polarons in a surface-doped layered semiconductor, MoS₂, in which a puzzling 2D superconducting dome with the critical temperature of 12 K was found recently^8,9,10,11. Using a high-resolution band mapping of charge carriers, we found strong band renormalizations collectively identified as a hitherto unobserved spectral function of Holstein polarons^{12,13,14,15,16,17,18}. The short-range nature of electron–phonon (e–ph) coupling in MoS₂ can be explained by its valley degeneracy, which enables strong intervalley coupling mediated by acoustic phonons. The coupling strength is found to increase gradually along the superconducting dome up to the intermediate regime, which suggests a bipolaronic pairing in the 2D superconductivity.

二维（2D）晶体已经出现为具有可调节载流子密度^1的一类材料。可以对2D半导体进行载流子掺杂来调制多体相互作用^2，并探索新颖的复合粒子。荷斯坦极化子是电子的一个小复合粒子，携带一束自感应的晶格形变（或声子）^3,4,5，它被提出在高温超导⁶和载流子迁移中起关键作用。设备⁷。在这里，我们报道了在表面掺杂的分层半导体MoS _2中发现荷斯坦极化子的发现，其中最近发现了一个临界温度为12 K的令人迷惑的2D超导圆顶^8,9,10,11。使用电荷载流子的高分辨率谱图，我们发现强谱带归一化被统一确定为荷斯坦极化子的迄今未观察到的谱函数^{12,13,14,15,16,17,18}。MoS ₂中电子-声子（e-ph）耦合的短距离性质可以通过其谷简并可以解释，这使得声子可以介导强的音程耦合。发现耦合强度沿着超导圆顶逐渐增加，直至达到中间态，这表明二维超导中的双极子对。