Few-layer MoS2 prepared by the chemical vapor deposition method is deposited on SiO2 samples with/without sulfide treatment in order to experimentally study the mechanism of conduction-type conversion in MoS2. The MoS2 thin film deposited on a SiO2 substrate with sulfide treatment shows n-type behavior, whereas the MoS2 thin film deposited on a SiO2 substrate without sulfide treatment exhibits p-type behavior. Experimental identification confirms that n-type conversion is due to a combined effect of the broken Si-O bonds and the formation of Si-S bonds at the SiO2 surface that results in the removal of oxygen dangling bonds and a change in the MoS2 SiO2 interaction. (C) 2016 Elsevier B.V. All rights reserved.