In this study, MoSe2 films with vertically standing layered structure were prepared by magnetron sputtering method with a thickness of ≈200 nm (see Figure S1 in the Supporting Information). The scalable sputtering method ensures the large‐area fabrication of high‐quality MoSe2 films with high uniformity, in contrast to the small size MoSe2 nanosheets obtained by exfoliation or thermal evaporation methods.55, 56 The as‐prepared MoSe2 film has trigonal phase (see Figure S2 in the Supporting Information). After deposition, the film was annealed in a rapid thermal processing systerm (RTP) at 800 °C in Ar for 20 min to further improve its crystal quality. Figure 1 a depicts the Raman spectra of the MoSe2 films of both as‐prepared and annealed MoSe2 films. Two typical Raman active modes, A1g and E2g, for MoSe2 are observed. The prominent A1g mode relates to the out‐of‐plane vibration of Se atoms, while the E2g mode is associated with the in‐plane vibration of Mo and Se atoms (see the inset in Figure 1a). Prior research results indicate that the change in layer number of MoSe2 nanosheets will cause a significant difference in the locations of scattering modes in Raman spectra; the E2g vibration will redshift, whereas the A1g vibration will blueshift, with increasing MoSe2 layer number.20, 57 Considering the large thickness of the MoSe2 film in this work, its Raman spectra are more likely to be identical to that of the MoSe2 bulk material or multilayer nanosheets. From Figure 1a, A1g and E2g scattering modes located at wave numbers of 240.3 and 288.1 cm−1, respectively, can be identified for the annealed film, which is consistent with previous reports for MoSe2 film.58, 59 It is reported that the obvious E2g peak usually occurs for monolayer MoSe2 nanosheet, whereas a thick MoSe2 film (≥2 layers) often exhibits a weak or invisible E2g peak.59, 60 Presumably, the unusually high E2g peak for the sputtering fabricated MoSe2 film may be attributed to the unique vertically standing layered structure.61 Figure 1b reveals an obvious movement of A1g peak from 235.2 cm−1 before annealing to 240.3 cm−1 after annealing, along with the decrease of peak width upon annealing. It is known that the A1g peak location of 240.3 cm−1 is more close to the standard value for high‐quality MoSe2 (240.6 cm−1).58, 59 Therefore, the Raman spectra clearly show that the film quality is significantly improved after annealing treatment. The components of the annealed MoSe2 film were further studied by X‐ray photoemission spectroscopy (XPS), as shown in Figure 1c,d. The Mo 3d shows two peaks at 229.2 and 232.3 eV, which can be attributed to the Mo 3d5/2 and Mo 3d3/2, respectively, confirming the existence of Mo4+.58, 62, 63 The peaks at 54.8 and 55.6 eV are attributed to the doublet Se 3d5/2 and Se 3d3/2, respectively, corresponding to the divalent selenide ions (Se2−).58, 62, 63