  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.
