论文标题
2D WS2在X射线光电子光谱和第一原理计算的SIO2底物上的界面特性
Interfacial properties of 2D WS2 on SiO2 substrate from x-ray photoelectron spectroscopy and first-principles calculations
论文作者
论文摘要
二维（2D）WS2膜沉积在SiO2晶片上，并通过高分辨率X射线光电学光谱（XPS）和第一原理计算研究了相关的界面特性。使用直接（间接）方法，发现单层WS2/SIO2接口处的价频段偏移（VBO）为3.97 eV（3.86 eV），传导带偏移量（CBO）为2.70 eV（2.81 eV）。此外，由于层间轨道耦合以及价值和传导带边缘的分裂，发现大量WS2/SIO2界面处的VBO（CBO）大约为0.48 eV（0.33 eV）。因此，WS2/SIO2异质结构具有I型能量波段对准。除了SIO2的理论带段较窄的理论带隙外，在实验和理论上获得的频段偏移是一致的。理论计算进一步揭示了每个s原子75 meV的结合能和状态的完全分离的部分密度，表明ws2单层和SIO2表面之间的相互作用较弱和可忽略不计的费米水平固定效应。我们合并的实验和理论结果提供了2D WS2/SIO2异质结构中足够的VBO和CBO以及弱相互作用的证明。
Two-dimensional (2D) WS2 films were deposited on SiO2 wafers, and the related interfacial properties were investigated by high-resolution x-ray photoelectron spectroscopy (XPS) and first-principles calculations. Using the direct (indirect) method, the valence band offset (VBO) at monolayer WS2/SiO2 interface was found to be 3.97 eV (3.86 eV), and the conduction band offset (CBO) was 2.70 eV (2.81 eV). Furthermore, the VBO (CBO) at bulk WS2/SiO2 interface is found to be about 0.48 eV (0.33 eV) larger due to the interlayer orbital coupling and splitting of valence and conduction band edges. Therefore, the WS2/SiO2 heterostructure has a Type I energy-band alignment. The band offsets obtained experimentally and theoretically are consistent except the narrower theoretical bandgap of SiO2. The theoretical calculations further reveal a binding energy of 75 meV per S atom and the totally separated partial density of states, indicating a weak interaction and negligible Fermi level pinning effect between WS2 monolayer and SiO2 surface. Our combined experimental and theoretical results provide proof of the sufficient VBOs and CBOs and weak interaction in 2D WS2/SiO2 heterostructures.
