Figure 2
Characterization of a monolayer MoS2 sample. (a) Optical image of monolayer MoS2 grown onto a SiO2/Si substrate. The constant color contrast indicates the uniform thickness of the MoS2 film. (b) Raman spectroscopy data for the sample. Two major peaks at 383.4 and 403.7 cm−1 correspond to the E12g and A1g modes of MoS2, respectively. The interval of 20.3 cm−1 between the two peaks indicates the monolayer of MoS2. (c) Current-voltage (I-V) curve measured on the sample. (d) Current measured by sweeping a gate voltage (VG). The threshold voltage (VTh) was estimated to be ~−40 V. (e) Current-normalized noise PSD (SI/I2) dependence on frequency. A 1/f noise behavior was observed. (f) SI/I2 at 30 Hz as a function of VG. The slope of the fitted line is −1.994, which is close to the value of −2 expected for carrier number fluctuations as the dominant origin for the noise generation.
