Intrinsic Electronic Transport Properties of High-Quality Monolayer and Bilayer MoS₂

Abstract

We report electronic transport measurements of devices based on monolayers and bilayers of the transition-metal dichalcogenide MoS 2 . Through a combination of in situ vacuum annealing and electrostatic gating we obtained ohmic contact to the MoS 2 down to 4 K at high carrier densities. At lower carrier densities, low temperature four probe transport measurements show a metal-insulator transition in both monolayer and bilayer samples. In the metallic regime, the high temperature behavior of the mobility showed strong temperature dependence consistent with phonon dominated transport. At low temperature, intrinsic field-effect mobilities greater than 1000 cm 2 /Vs were observed for both monolayer and bilayer devices. Mobilities extracted from Hall effect measurements were several times lower and showed a strong dependence on density, likely caused by screening of charged impurity scattering at higher densities.

Probing the electron states and metal-insulator transition mechanisms in molybdenum disulphide vertical heterostructures

“…6a) and monolayer (Fig. 6b) MoS 2 are clearly shown by the conductivity s, at different temperatures, similar to previous reports [3][4][5][6] . The MIT occurs at nB6 Â 10 12 cm À 2 for multilayer MoS 2 and nB1.1 Â 10 12 cm À 2 for monolayer MoS 2 , consistent with the capacitance data.…”

“…M olybdenum disulphide (MoS 2 ), an n-type semiconductor [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] , shows novel properties such as superconductivity 6 , controllable valley polarization 17,18 and metal-insulator transition [3][4][5][6] (MIT). In MoS 2 field-effect transistors (FETs), gate-induced charge carriers transport in a thin layer near the surface of MoS 2 and are vulnerable to charge impurities and different types of disorder 2,3,12,14,19,20 .…”

Repairing atomic vacancies in single-layer MoSe2 field-effect transistor and its defect dynamics

“…We find that the unprocessed sample presents the mobility of 0.1 cm 2 /Vs while the processed sample holds the mobility of 30 ± 6 cm 2 /Vs (consider the contact resistance). 31,[38][39][40][41] It shows great mobility improvement by 2-3 orders of magnitude after the EDTA processing. It it noted that the device is turned on when back gate voltage is positive, which is the signature of the electron dominance and the mobility data obtained above are for electrons.…”

Low-Resistance 2D/2D Ohmic Contacts: A Universal Approach to High-Performance WSe2, MoS2, and MoSe2 Transistors

“…Furthermore, the 1T phase MoS 2 is thermally unstable above 100 o C. The availability of a variety of semiconducting TMDs such as MoSe 2 , WS 2 and WSe 2 with different band structures and charge neutrality levels offers additional distinct properties and opportunities for device applications. 5,6,8,9,13,[26][27][28][29][30][31][32][33][34][35][36][37] However, the variation of electron affinity, band gap, and band alignments also presents significant challenges to contact engineering. To unlock the full potential of TMDs as channel materials for high-performance thin-film transistors, highly effective and versatile contact strategies for making low-resistance ohmic contacts are needed.…”