Fig. 1. （a） The AFM image of a MoS₂ film on a c-Al₂O₃ substrate， The（b） XRD and（c） Raman spectra of the MoS₂ film，（d） The PL spectra of a MoS₂ film

Fig. 2. （a） The survey XPS spectra of a film deposited for 150 pulses， The XPS spectra and its deconvolution of（b） Mo 3d and（c） S 2P core level

Fig. 3. （a） The optical image of a randomly selected 40 μm × 40 μm area，（b） The mapping of the frequency differences between E¹_2g and A_1g peaks，（c） The mapping of the intensity of the A_1g peak. The mapping of the excitonic peak（d） positions and（e） intensity，（f） The Raman spectra for different layers

Fig. 4. （a） The schematic of the photoresponse measurement progress，（b） The time-resolved photocurrent of MoS₂ films with different layers，（c） The layer-dependent rising（τ_up） and decay response times（τ_down）. The inset presents the rising and decay response times of the monolayer MoS₂ film，（d） The time-resolved photoresponse of a monolayer MoS₂ film at 200 K， 270 K and 370 K，（e） The temperature-dependent photoresponse of a monolayer MoS₂ film. The inset presents the temperature-dependent I_ph，（f） The temperature-dependent rising（τ_up） and decay response times（τ_down）