Defect-Free Copolymer Gate Dielectrics for Gating MoS₂ Transistors

Abstract

In this study, the poly (2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane-co-cyclohexyl methacrylate) [p(V4D4-co-CHMA)] copolymer was developed for use as a gate dielectric in molybdenum disulfide (MoS 2 ) field-effect transistors (FETs). The p(V4D4-co-CHMA) copolymer was synthesized via the initiated chemical vapor deposition (iCVD) of two types of monomers: 2,4,6,8-tetramethyl-2,4,6,8tetravinylcyclotetrasiloxane (V4D4) and cyclohexyl methacrylate (CHMA). Four vinyl groups of V4D4 monomers and cyclohexyl groups of CHMA monomers were introduced to enhance the electrical strength of gate dielectrics through the formation of a highly crosslinked network and to reduce the charge trap densities at the MoS 2 −dielectric interface, respectively. The iCVD-grown p(V4D4-co-CHMA) copolymer films yielded a dielectric constant of 2.3 and a leakage current of 3.8 × 10 −11 A/cm 2 at 1 MV/cm. The resulting MoS 2 FETs with p(V4D4-co-CHMA) gate dielectrics exhibited excellent electrical properties, including an electron mobility of 35.1 cm 2 /V s, a subthreshold swing of 0.2 V/dec, and an on−off current ratio of 2.6 × 10 6 . In addition, the environmental and operational stabilities of MoS 2 FETs with p(V4D4-co-CHMA) top-gate dielectrics were superior to those of devices with SiO 2 back-gate dielectrics. The use of iCVD-grown copolymer gate dielectrics as demonstrated in this study provides a novel approach to realizing next-generation two-dimensional electronics.

High-Performance Layered Perovskite Transistors and Phototransistors by Binary Solvent Engineering

“…A larger τ d indicates a smaller probability of a trapping event occurring resulting from the reduced density of charge trap sites. 33 Then, a complementary inverter was demonstrated (detailed inverter connections shown in Figure S6) with n-channel InGaZnO and p-channel DMF:EA 20% (PEA) 2 SnI 4 TFTs, revealing the great potential for perovskite TFT use in logic circuits. Figure 3f shows the inverter diagram and voltage transfer characteristics with a rapid voltage transition and a high peak gain of ∼30 (dual-sweep inverter characteristics are shown in Figure S7).…”

Effect of Electron Irradiation on the Transport and Field Emission Properties of Few-Layer MoS2 Field-Effect Transistors

“…Molybdenum disulfide (MoS 2 ) is a two-dimensional (2D) layered material, one of the transition-metal dichalcogenides (TMDs), with layers that are weakly held together by van der Waals forces. Energy band gap in MoS 2 varies from 1.2 eV (indirect) in the bulk to 1.8–1.9 eV (direct) in monolayer. − Despite a low field-effect mobility (limited to few hundreds cm 2 V –1 s –1 on suspended samples), MoS 2 -based devices have attracted growing interest for several applications, such as field-effect transistors (FETs), ,− sensors, − spintronic devices, field emission cathodes, , synaptic computation for neuroscience, and so forth.…”

Flexible electronics based on 2D transition metal dichalcogenides

“…The copolymer dielectric, poly(2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane-co-cyclohexyl methacrylate) [p(V4D4-co-CHMA)], has been deposited via the CVD method on a MoS 2based TFT. 208 Owing to the conjugated network structure and the cyclohexyl groups, [p(V4D4-co-CHMA)] enhances the electrical strength and effectively suppresses the charge traps at the MoS 2 interface. Ion gels are another class of exible dielectrics for TMD-based TFTs (Fig.…”