High-Performance Flexible MoS2 Transistors Using Au/Cr/Al/Au as Source/Drain Electrodes

2D transition metal dichalcogenides such as molybdenum disulfide (MoS2) are promising candidates for flexible electronics because of their bandgap tunability, high carrier mobility, and mechanical flexibility. However, flexible MoS2 field effect transistors (FETs) are typically faced with high contact resistance which is identified as a critical limiting factor to their potential applications. The present work successfully addresses this challenge by using Al contacts without any annealing process. It is found that the contact resistance is strongly coupled to the Al thickness, increasing the Al thickness is beneficial to reduce the contact resistance. The observed variation in the device electrical characteristics can be associated with the formation of the natural aluminum oxide (AlxOy) film at the interface. An ultrathin Au insert layer can further advance the device performance. An optimal contact resistance of 2.03 k? and an on/off current ratio of 1.57 x 109 can be achieved in the flexible MoS2 FETs using Au/Cr/Al/Au as source/drain electrodes. Furthermore, no apparent degradation in the device properties is observed under systematic cyclic bending testing with bending radii of 18 and 15 mm. The successful integration of Au/Cr/Al/Au source/drain electrodes into MoS2 FETs promises its potential application in flexible electronic devices.