Mist chemical vapor deposition of crystalline MoS <sub>2</sub> atomic layer films using sequential mist supply mode and its application in field-effect transistors
Abdul Kuddus, Arifuzzaman Rajib, Kojun Yokoyama, Tomohiro Shida, Keiji Ueno, Hajime Shirai
Abstract
Abstract Molybdenum disulfide (MoS 2 ) mono/bilayer have been systematically investigated using atmospheric-pressure mist chemical vapor deposition (mist CVD) from (NH 4 ) 2 MoS 4 dissolved in N-methyl-2-pyrrolidone as a precursor. Film deposition was performed by alternating MoS 2 mist storage within a closed chamber and mist exhaust, i.e. sequential mist supply mode at different furnace temperatures, storage times of precursor, and repetition cycles of mist supply on thermally grown SiO 2 ( th -SiO 2 ) and mist-CVD grown Al 1 −x Ti x O y (ATO) layers coated on p + -Si substrates. The average size of the MoS 2 flake and their number of stack layers could be controlled by tuning the deposition parameters combined with substrate pretreatment. Field-effect transistors with MoS 2 atomic mono/bilayer as a channel layer exhibited mobility up to 31–40 (43–55) cm 2 V −1 s −1 with a threshold voltage of −1.6 (−0.5) V, subthreshold slope of 0.8 (0.11) V dec. −1 , and on/off ratio of 3.2 × 10 4 (3.6 × 10 5 ) on th -SiO 2 (ATO) layers as gate dielectric layers without mechanical exfoliation. These findings imply that mist CVD is available for the synthesis of metal transition metal dichalcogenide and metal oxide layers as channel and gate dielectric layers, respectively.