Unexpected Electron Transport Suppression in a Heterostructured Graphene–MoS₂Multiple Field-Effect Transistor Architecture

Abstract

We demonstrate a graphene–MoS2 architecture integrating multiple field-effect transistors (FETs), and we independently probe and correlate the conducting properties of van der Waals coupled graphene–MoS2 contacts with those of the MoS2 channels. Devices are fabricated starting from high-quality single-crystal monolayers grown by chemical vapor deposition. The heterojunction was investigated by scanning Raman and photoluminescence spectroscopies. Moreover, transconductance curves of MoS2 are compared with the current–voltage characteristics of graphene contact stripes, revealing a significant suppression of transport on the n-side of the transconductance curve. On the basis of ab initio modeling, the effect is understood in terms of trapping by sulfur vacancies, which counterintuitively depends on the field effect, even though the graphene contact layer is positioned between the backgate and the MoS2 channel.

Electrostatic control of photoluminescence from A and B excitons in monolayer molybdenum disulfide

“…The zero strain and zero doping lines crossed at a point, corresponding to the literature values ( E 1 2g = 385.0.2 cm −1 and A 1g = 405.0 cm −1 ) of the peak frequencies for a suspended MoS 2 membrane. 36–38 The correlation plot of the A 1g peak positions versus the E 1 2g peak positions suggest that the Mo-rich MoS 2 grown on SiO 2 shows a higher electron doping (2–3 × 10 12 cm −2 ) than that of the S-rich MoS 2 (0.5–1 × 10 12 cm −2 ). Raman peaks of both Mo-rich and S-rich MoS 2 were located near a strain line at ε = 0.2%, indicting no obvious difference in the strain effect.…”

Strain-Tunable Ultrastable MoS2/Fluorographene Hybrid Photodetectors of High Responsivity

“…To understand the successful charge transfer between the FG and MS, a A 1g vs E 2g peak graph is plotted for pristine MS and FGMS heterostructures. Assuming a linear relationship between the peak frequency (ω) and carrier concentration( n ) for MS (details are given in the Supporting Information’s discussion part), the Raman frequencies are related to strain (ε) and carrier concentration ( n ) as follows , ε = K n ( 1 ) normalΔ ω 2 − K n ( 2 ) normalΔ ω 1 2 γ 1 ω 1 0 K n ( 2 ) − 2 γ 2 ω 2 0 K n ( 1 ) n = γ 1 ω 1 0 normalΔ ω 2 − γ 2 ω 2 0 normalΔ ω 1 γ 1 ω 1 0 K n ( 2 ) − γ 2 ω 2 0 K n ( 1 ) where γ and K are the Grüneisen parameter and the linear proportionality constant between ω and n , respectively, and 1 and 2 are for E 2g and A 1g peaks of MoS 2 , respectively. The blue and red lines for ε and n in Figure d, respectively, are drawn according to eqs and .…”

“…To understand the successful charge transfer between the FG and MS, a A 1g vs E 2g peak graph is plotted for pristine MS and FGMS heterostructures. Assuming a linear relationship between the peak frequency (ω) and carrier concentration(n) for MS (details are given in the Supporting Information's discussion part), the Raman frequencies are related to strain (ε) and carrier concentration (n) as follows 35,36 (1)…”

Emerging van der Waals Dielectrics of Inorganic Molecular Crystals for 2D Electronics

“…The FET architecture is a widely used platform in condensed matter physics, especially for investigations of electron transport behaviors. , Various 2D crystals with interesting phenomena of electron transport such as strong correlation effects, superconductivity, magnetism, and topological phases have attracted tremendous research interests . The solid-state device is commonly required to modulate the electron density and apply an electric field.…”