Millimeter-scale layered MoSe2 grown on sapphire and evidence for negative magnetoresistance

Abstract

Molecular beam epitaxy technique has been used to deposit a single layer and a bilayer of MoSe2 on sapphire. Extensive characterizations including in-situ and ex-situ measurements show that the layered MoSe2 grows in a scalable manner on the substrate and reveals characteristics of a stoichiometric 2H-phase. The layered MoSe2 exhibits polycrystalline features with domains separated by defects and boundaries. Temperature and magnetic field dependent resistivity measurements unveil a carrier hopping character described within two-dimensional variable range hopping mechanism. Moreover, a negative magnetoresistance was observed, stressing a fascinating feature of the charge transport under the application of a magnetic field in the layered MoSe2 system. This negative magnetoresistance observed at millimeter-scale is similar to that observed recently at room temperature inWS2 flakes at a micrometer scale [Zhang et al., Appl. Phys. Lett. 108, 153114 (2016)]. This scalability highlights the fact that the underlying physical mechanism is intrinsic to these two-dimensional materials and occurs at very short scale.

van der Waals epitaxy of Mn-doped MoSe2 on mica

“…At this regime, the carriers get localized, leading to the substantial increase of the resistivity. In the hightemperature regime, we found that the resistivity of the Mn-doped MoSe 2 layer with the structure M is one order of magnitude smaller than that of the undoped layer for the same range of temperature as reported earlier [21]. That clearly indicates doping characteristic of Mn dopants on electrical properties.…”

Highly Oriented Atomically Thin Ambipolar MoSe2 Grown by Molecular Beam Epitaxy

“… 37 , 38 These results indicate that charge carrier transport is strongly influenced by the disorder in the film. 23 , 39 …”

Growth of Nanocrystalline MoSe2 Monolayers on Epitaxial Graphene from Amorphous Precursors

“…The films grown on buffer layer and MLG samples appear to be similar in structure, illustrating that the MER synthesis may be applicable without the restriction to a specific substrate. While grain sizes so far do not challenge the micrometer‐sized flakes grown from CVD approaches, they seem to compare well with films grown by conventional MBE techniques which are in the range of several tens of nanometers …”