Thickness-dependent mobility in two-dimensional MoS₂transistors

Abstract

Two-dimensional (2D) semiconductors such as mono and few-layer molybdenum disulphide (MoS 2 ) are very promising for integration in future electronics as they represent the ultimate miniaturization limit in the vertical direction. While monolayer MoS 2 attracted considerable attention due to its broken inversion symmetry, spin/valley coupling and the presence of a direct band gap, few-layer MoS 2 remains a viable option for technological application where its higher mobility and lower contact resistance are believed to offer an advantage. However, it remains unclear whether multilayers are intrinsically superior or if they are less affected by environmental effects. Here, we report the first systematic comparison of the field-effect mobilities in mono-, bi-and trilayer MoS 2 transistors after thorough in situ annealing in vacuum. We show that the mobility of field-effect transistors (FETs) based on monolayer MoS 2 is significantly higher than that of FETs based on two or three layers. We demonstrate that it is important to remove the influence of gaseous adsorbates and water before comparing mobilities, as monolayers exhibit the highest sensitivity to ambient air exposure. In addition, we study the influence of the substrate roughness and show that this parameter does not affect FET mobilities.

Air and Water‐Stable n‐Type Doping and Encapsulation of Flexible MoS2 Devices with SU8

“…Aging of the doping source itself and the influence of the environment due to O 2 and H 2 O adsorbates [26][27][28] are the two main sources of instability. Aging of the doping source itself and the influence of the environment due to O 2 and H 2 O adsorbates [26][27][28] are the two main sources of instability.…”

“…[17] Various molecular surface doping methods based on wet chemical treatment have been widely explored, but most of them are not air-stable and are difficult to control. [26][27][28] Al 2 O 3 , HfO 2 , and other high-κ inorganic dielectrics have been commonly used as encapsulation layers for layered 2D devices. [22,23] Stable and controllable doping could be achieved using Cs 2 CO 3 thin films by varying the film thickness [24] or phosphorus silicate glass (PSG) substrates through thermal and optical activation; [25] however, brittle Cs 2 CO 3 films and PSG substrates are not suitable for flexible electronics.…”

“…[26][27][28] Al 2 O 3 , HfO 2 , and other high-κ inorganic dielectrics have been commonly used as encapsulation layers for layered 2D devices. It is well known that the performance of MoS 2 FETs degrades in air due to surface adsorption of O 2 and H 2 O.…”

Characteristics of layered tin disulfide deposited by atomic layer deposition with H2S annealing

“…9,10 Most TMDs that possess good electrical properties are formed by mechanical exfoliation because high-quality crystalline TMDs can be obtained by this method. [9][10][11] However, this method has low productivity and is not compatible with current device manufacturing processes due to scale limitations involving uniform synthesis. Another method to obtain TMDs is chemical vapor deposition (CVD), which uniformly produces large, high-quality TMDs.…”

Spin-dependent thermoelectric effects in Fe-C6 doped monolayer MoS2

“…), and they doped monolayer MoS 2 with Fe-C 6 and Fe-O 6 clusters acquiring two DMSs. The devices based on MoS 2 had also been designed 23–31 .…”