2D platinum diselenide (PtSe₂) has received significant attention for 2D transistor applications due to its high carrier mobility. Here, using molecular beam epitaxy, the growth of 2D PtSe₂ is investigated on highly oriented pyrolytic graphite (HOPG) and their electronic properties are unveiled via X-ray photoelectron spectroscopy, Raman spectra, and scanning tunnelling microscopy/spectroscopy as well as density functional theory (DFT) calculations. PtSe₂ adopts a layer-by-layer growth mode on HOPG and shows a decreasing bandgap with increasing layer number. For the layer numbers from one to four, PtSe₂ has bandgaps of 2.0 ± 0.1, 1.1 ± 0.1, 0.6 ± 0.1, and 0.20 ± 0.1 eV, respectively, and becomes semimetal from the fifth layer. DFT calculations reproduce the layer-dependent evolution of both the bandgap and band edges, suggest an indirect bandgap structure, and elucidate the underlying physics at the atomic level.

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MBE-Grown PtSe2 的精确层相关电子结构

由于其高载流子迁移率，二维二硒化铂 (PtSe ₂ ) 在二维晶体管应用中受到了极大的关注。在这里，使用分子束外延，在高度取向的热解石墨 (HOPG) 上研究了 2D PtSe ₂的生长，并通过 X 射线光电子能谱、拉曼光谱、扫描隧道显微镜/光谱以及密度泛函揭示了它们的电子特性理论 (DFT) 计算。PtSe ₂在 HOPG 上采用逐层生长模式，随着层数的增加，带隙逐渐减小。用于从一个层编号为四，PTSE ₂具有2.0带隙 ± 0.1，1.1  ± 0.1，0.6  ± 分别为 0.1 和 0.20  ± 0.1 eV，并从第五层变成半金属。DFT 计算再现了带隙和带边缘的层相关演化，提出了间接带隙结构，并阐明了原子水平的基础物理。