Seeded growth of highly crystalline molybdenum disulphide monolayers at controlled locations

Monolayer transition metal dichalcogenides are materials with an atomic structure complementary to graphene but diverse properties, including direct energy bandgaps, which makes them intriguing candidates for optoelectronic devices. Various approaches have been demonstrated for the growth of molybdenum disulphide (MoS 2 ) on insulating substrates, but to date, growth of isolated crystalline flakes has been demonstrated at random locations only. Here we use patterned seeds of molybdenum source material to grow flakes of MoS 2 at predetermined locations with micrometre-scale resolution. MoS 2 flakes are predominantly monolayers with high material quality, as confirmed by atomic force microscopy, transmission electron microscopy and Raman and photoluminescence spectroscopy. As the monolayer flakes are isolated at predetermined locations, transistor fabrication requires only a single lithographic step. Device measurements exhibit carrier mobility and on/off ratio that exceed 10 cm 2 V −1 s −1 and 10 6 , respectively. The technique provides a path for in-depth physical analysis of monolayer MoS 2 and fabrication of MoS 2 -based integrated circuits. Although synthesis of high-quality MoS 2 has been demonstrated, growth of monolayer MoS 2 at controlled locations is highly desirable for applications. Here, the authors introduce a method where patterned seeds of molybdenum source material are used to grow isolated flakes at predetermined locations.