Flexible integrated circuits and multifunctional electronics based on single atomic layers of MoS₂and graphene

Abstract

Two-dimensional materials, such as graphene and its analogues, have been investigated by numerous researchers for high performance flexible and conformal electronic systems, because they offer the ultimate level of thickness scaling, atomically smooth surfaces and high crystalline quality. Here, we use layer-by-layer transfer of large area molybdenum disulphide (MoS2) and graphene grown by chemical vapor deposition (CVD) to demonstrate electronics on flexible polyimide (PI) substrates. On the same PI substrate, we are able to simultaneously fabricate MoS2 based logic, non-volatile memory cells with graphene floating gates, photo-detectors and MoS2 transistors with tunable source and drain contacts. We are also able to demonstrate that these flexible heterostructure devices have very high electronic performance, comparable to four point measurements taken on SiO2 substrates, with on/off ratios >10(7) and field effect mobilities as high as 16.4 cm(2) V(-1) s(-1). Additionally, the heterojunctions show high optoelectronic sensitivity and were operated as photodetectors with responsivities over 30 A W(-1). Through local gating of the individual graphene/MoS2 contacts, we are able to tune the contact resistance over the range of 322-1210 Ω mm for each contact, by modulating the graphene work function. This leads to devices with tunable and multifunctional performance that can be implemented in a conformable platform.

P‐Type Polar Transition of Chemically Doped Multilayer MoS2 Transistor

“…Since R c limited the polar transition of MoS 2 from NFET to PFET, contact engineering efforts aimed at reducing R c were implemented for achieving high‐performance MoS 2 PFETs. Here, we applied a graphene buffer layer at Pd‐MoS 2 interface, expecting to induce hole injection layer for MoS 2 since high work function of graphene is formed after AuCl 3 doping and graphene work function can be further increased by effective gating . A schematic diagram of the MoS 2 transistor prepared with a graphene buffer layer is shown in Figure a.…”

Wafer-Scale Fabrication of Two-Dimensional PtS2/PtSe2 Heterojunctions for Efficient and Broad band Photodetection

“…Encouragingly, 2D transition metal dichalcogenides (TMDs), one important member from the family of atomically thin van der Waals materials, has been widely studied and proved to be of great potential for the applications of future optoelectronics owing to their outstanding electronic, optical, mechanical properties and the strong light-matter interactions [7][8][9] . TMDs have extended bandgap tunability through composition 10 , thickness 11,12 and possibly even strain control 13 offering infinite flexibility to design 2D junctions 4, [14][15][16][17][18] , which has been used in photovoltaics, photodiodes and light emitters 11,15,19 , and could overcome some of the existing problems in conventional junction devices 20 . Therefore, driven by the diversity and considerable wide coverage properties of TMDs materials, artificial 2D van der Waals junctions have been fabricated using either homogeneous or heterogeneous 2D materials 17,21 .…”

Highly Stretchable Electrodes on Wrinkled Polydimethylsiloxane Substrates

“…Towards more flexible but also stretchable devices, micro/nano electrodes and wires are one of the most important components that require new materials and new mechanical designs 6 . Carbon black based elastic conductors have been investigated but their strain induced resistance variations are still high.…”