High-Performance, Highly Bendable MoS₂ Transistors with High-K Dielectrics for Flexible Low-Power Systems

Abstract

While there has been increasing studies of MoS2 and other two-dimensional (2D) semiconducting dichalcogenides on hard conventional substrates, experimental or analytical studies on flexible substrates has been very limited so far, even though these 2D crystals are understood to have greater prospects for flexible smart systems. In this article, we report detailed studies of MoS2 transistors on industrial plastic sheets. Transistor characteristics afford more than 100x improvement in the ON/OFF current ratio and 4x enhancement in mobility compared to previous flexible MoS2 devices. Mechanical studies reveal robust electronic properties down to a bending radius of 1 mm which is comparable to previous reports for flexible graphene transistors. Experimental investigation identifies that crack formation in the dielectric is the responsible failure mechanism demonstrating that the mechanical properties of the dielectric layer is critical for realizing flexible electronics that can accommodate high strain. Our uniaxial tensile tests have revealed that atomic-layer-deposited HfO2 and Al2O3 films have very similar crack onset strain. However, crack propagation is slower in HfO2 dielectric compared to Al2O3 dielectric, suggesting a subcritical fracture mechanism in the thin oxide films. Rigorous mechanics modeling provides guidance for achieving flexible MoS2 transistors that are reliable at sub-mm bending radius.

Photo-FETs: Phototransistors Enabled by 2D and 0D Nanomaterials

“…Monolayer MoS2 photodetectors are especially promising for flexible and semitransparent device concepts due to its mechanical flexibility and strength [52][53][54][55] . One of the most intriguing properties of monolayer MoS2 is its large direct bandgap of 1.8eV, which leads to high absorption efficiency 56,57 and large electrical on/off ratios.…”

Two-dimensional flexible nanoelectronics

“…In particular, flexible nanoelectronics stand to greatly benefit from the development of 2D crystals because their unmatched combination of device physics and device mechanics is accessible on soft polymeric or plastic substrates 17,18,32,33 , which can enable the long sought after large-area high-performance flexible devices that can be manufactured at economically viable scales. As a result, existing flexible technology is expected to be transformed from low-cost commodity applications, such as radio-frequency identification tags and sensors, to integrated nanosystems with electronic performance comparable to silicon devices, in addition to affording mechanical flexibility and manufacturing form-factor beyond the capability of conventional semiconductor technology 34 .…”

Electronic transport and device prospects of monolayer molybdenum disulphide grown by chemical vapour deposition

“…4) makes it a potential material for not only digital electronics but also numerous photonic applications such as light emitter 5 , photodetectors 6,7 and solar cells 8 . Excellent mechanical flexibility of MoS 2 also makes it a compelling semiconducting material for flexible electronics 9,10 . Most existing studies and device demonstrations were performed on exfoliated MoS 2 flakes [11][12][13][14][15][16][17][18][19] .…”