We report on the transport and low-frequency noise measurements of MoS2 thin-film transistors with thin (2-3 atomic layers) and thick (15-18 atomic layers) channels. The back-gated transistors made with the relatively thick MoS2 channels have advantages of the higher electron mobility and lower noise level. The normalized noise spectral density of the low-frequency 1/f noise in thick MoS2 transistors is of the same level as that in graphene. The MoS2 transistors with the atomically thin channels have substantially higher noise levels. It was established that, unlike in graphene devices, the noise characteristics of MoS2 transistors with thick channels (15-18 atomic planes) could be described by the McWhorter model. Our results indicate that the channel thickness optimization is crucial for practical applications of MoS2 thin-film transistors.
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