We report the fabrication of back-gated field-effect transistors (FETs) using ultra-thin, mechanically exfoliated MoSe2 flakes. The MoSe2 FETs are n-type and possess a high gate modulation, with On/Off ratios larger than 106. The devices show asymmetric characteristics upon swapping the source and drain, a finding explained by the presence of Schottky barriers at the metal contact/MoSe2 interface. Using four-point, back-gated devices, we measure the intrinsic conductivity and mobility of MoSe2 as a function of gate bias, and temperature. Samples with a room temperature mobility of ∼ 50 cm2/V·s show a strong temperature dependence, suggesting phonons are a dominant scattering mechanism.

Field-effect transistors and intrinsic mobility in ultra-thin MoSe2 layers

We report the fabrication of back-gated field-effect transistors (FETs) using ultra-thin, mechanically exfoliated MoSe2 flakes. The MoSe2 FETs are n-type and possess a high gate modulation, with On/Off ratios larger than 106. The devices show asymmetric characteristics upon swapping the source and drain, a finding explained by the presence of Schottky barriers at the metal contact/MoSe2 interface. Using four-point, back-gated devices we measure the intrinsic conductivity and mobility of MoSe2 as a function of gate bias, and temperature. Samples with a room temperature mobility of ~50 cm2/V.s show a strong temperature dependence, suggesting phonons are a dominant scattering mechanism.

In the quest to discover the properties of planar semiconductors, two-dimensional molybdenum trioxide and dichalcogenides have recently attracted a large amount of interest. This family, which includes molybdenum trioxide (MoO 3 ), disulphide (MoS 2 ), diselenide (MoSe 2 ) and ditelluride (MoTe 2 ), possesses many unique properties that make its compounds appealing for a wide range of applications. These properties can be thickness dependent and may be manipulated via a large number of physical and chemical processes. In this Feature Article, a comprehensive review is delivered of the fundamental properties, synthesis techniques and applications of layered and planar MoO 3 , MoS 2 , MoSe 2 , and MoTe 2 along with their future prospects.

Two-Dimensional Molybdenum Trioxide and Dichalcogenides

Colloidal 2D nanosheets of MoS2 and other transition metal dichalcogenides through liquid-phase exfoliation.

We report the colloidal synthesis of substrate-free MoSe2 nanostructures with a uniform flower-like morphology and tunable average diameters that range from approximately 50–250 nm. The MoSe2 nanoflowers contain a large population of highly crystalline few-layer nanosheets that protrude from a central core. Aliquot studies and control experiments indicate that the nanoflowers are generated through a two-step process that involves the formation of a core in the early stages of the reaction followed by outward nanosheet growth that can be controlled based on the concentrations of reagents. The effects of laser-induced local heating, bulk-scale heating using a temperature stage, and nanostructuring on the ability to trigger and tune interlayer decoupling were also investigated. Notably, laser-induced local heating results in dynamic and reversible interlayer decoupling. Such capabilities provide a pathway for achieving quasi-two-dimensional behavior in three-dimensionally structured and colloidally synthesiz...

Formation and Interlayer Decoupling of Colloidal MoSe2 Nanoflowers

Nanomaterials based on molybdenum diselenide

Polyaniline, poly(N-methyl aniline), poly(2-ethyl aniline) and poly(2-propyl aniline) were intercalated into layered molybdenum diselenide by using the exfoliation/restacking property of LixMoSe2. MoSe2 was reacted with n-butyllithium to form LixMoSe2. The LixMoSe2 was exfoliated in N-methylformamide (NMF) with the help of ultrasonication which lead to the formation of single layers of MoSe2. Addition of NMF solutions of the polymers to the exfoliated layers resulted in their intercalation into MoSe2. The products were characterized by powder X-ray diffraction. Fourier transform infra-red spectroscopy, and four-probe van der Pauw technique electrical conductivity measurements are reported here for the first time.

https://link.springer.com/content/pdf/10.1007%2Fs10904-013-9981-z.pdf

Hao Xu

Papers

Nanomaterials based on molybdenum diselenide

Nanomaterials Based on Polyanilines and MoSe2