Fabrication and Transfer of Flexible Few-Layers MoS₂ Thin Film Transistors to Any Arbitrary Substrate

Abstract

Recently, transition metal dichalcogenides (TMDCs) have attracted interest thanks to their large field effective mobility (>100 cm(2)/V · s), sizable band gap (around 1-2 eV), and mechanical properties, which make them suitable for high performance and flexible electronics. In this paper, we present a process scheme enabling the fabrication and transfer of few-layers MoS2 thin film transistors from a silicon template to any arbitrary organic or inorganic and flexible or rigid substrate or support. The two-dimensional semiconductor is mechanically exfoliated from a bulk crystal on a silicon/polyvinyl alcohol (PVA)/polymethyl methacrylane (PMMA) stack optimized to ensure high contrast for the identification of subnanometer thick flakes. Thin film transistors (TFTs) with structured source/drain and gate electrodes are fabricated following a designed procedure including steps of UV lithography, wet etching, and atomic layer deposited (ALD) dielectric. Successively, after the dissolution of the PVA sacrificial layer in water, the PMMA film, with the devices on top, can be transferred to another substrate of choice. Here, we transferred the devices on a polyimide plastic foil and studied the performance when tensile strain is applied parallel to the TFT channel. We measured an electron field effective mobility of 19 cm(2)/(V s), an I(on)/I(off)ratio greater than 10(6), a gate leakage current as low as 0.3 pA/μm, and a subthreshold swing of about 250 mV/dec. The devices continue to work when bent to a radius of 5 mm and after 10 consecutive bending cycles. The proposed fabrication strategy can be extended to any kind of 2D materials and enable the realization of electronic circuits and optical devices easily transferrable to any other support.

Wafer-scale design of lightweight and transparent electronics that wraps around hairs

“…This could include a complete set of basic electronic ingredients, that is, semiconductors (amorphous oxide semiconductors), metals and high-K dielectrics. A similar approach has been used to realize flexible molybdenum disulphide, MoS 2 , transistors 30 . Such large spectrum of possibilities can lead to ultra flexible devices in electronics and photonics and find application in ultralight solar cells, implantable devices, rollable and transparent displays, smart-skin and electronic textiles.…”

Seeded growth of highly crystalline molybdenum disulphide monolayers at controlled locations

“…T he presence of an intrinsic direct energy bandgap in molybdenum disulphide (MoS 2 ) monolayers makes this two-dimensional material of both fundamental and technological interest [1][2][3][4][5][6][7][8][9][10] . Several synthetic methods have been reported, including sulphiding of Mo thin film 11 , and annealing of ammonium tetrathiomolybdate, which has both Mo and S components 12 .…”

Newborn 2D materials for flexible energy conversion and storage

“…Some newborn TMDs have been greatly explored in providing a huge potential for the development of flexible SCs with higher electrochemical performance. 6 and a threshold voltage of about -2 V [50]. In attempting to improve the coulombic efficiency, a solid-state, flexible, asymmetric SC with good rate, cycling stability, and improved energy density was created.…”