Alloying enables engineering of the electronic structure of semiconductors for optoelectronic applications. Due to their similar lattice parameters, the two-dimensional semiconducting transition metal dichalcogenides of the MoWSeS group (MX₂ where M = Mo or W and X = S or Se) can be grown as high-quality materials with low defect concentrations. Here we investigate the atomic and electronic structure of Mo_(1−x)W _x S₂ alloys using a combination of high-resolution experimental techniques and simulations. Analysis of the Mo and W atomic positions in these alloys, grown by chemical vapour transport, shows that they are randomly distributed, consistent with Monte Carlo simulations that use interaction energies determined from first-principles calculations. Electronic structure parameters are directly determined from angle resolved photoemission spectroscopy measurements. These show that the spin–orbit splitting at the valence band edge increases linearly with W content from MoS₂ to WS₂, in agreement with linear-scaling density functional theory predictions. The spin–orbit splitting at the conduction band edge is predicted to reduce to zero at intermediate compositions. Despite this, polarisation-resolved photoluminescence spectra on monolayer Mo_0.5W_0.5S₂ show significant circular dichroism, indicating that spin-valley locking is retained. These results demonstrate that alloying is an important tool for controlling the electronic structure of MX₂ for spintronic and valleytronic applications.

合金化能够为光电应用设计半导体的电子结构。由于它们的晶格参数相似，MoWSeS 组（MX ₂，其中 M = Mo 或 W 和 X = S 或 Se）的二维半导体过渡金属二硫属化物可以生长为具有低缺陷浓度的高质量材料。在这里，我们研究了 Mo _{(1− x )} W _x S ₂的原子和电子结构 使用高分辨率实验技术和模拟相结合的合金。对这些合金中 Mo 和 W 原子位置的分析表明，它们是随机分布的，这与使用第一性原理计算确定的相互作用能的蒙特卡罗模拟一致。电子结构参数直接由角分辨光发射光谱测量确定。这些表明价带边缘的自旋轨道分裂随 W 含量从 MoS ₂到 WS ₂线性增加，与线性标度密度泛函理论预测一致。导带边缘的自旋轨道分裂预计在中间组成时会减少到零。尽管如此，单层Mo _0.5 W _0.5 S ₂上的偏振分辨光致发光光谱显示出明显的圆二色性，表明自旋谷锁定得以保留。这些结果表明合金化是控制 MX ₂电子结构的重要工具，用于自旋电子和谷电子应用。