Selective and localized laser annealing effect for high-performance flexible multilayer MoS2 thin-film transistors

Abstract

We report the use of ultra-short, pulsed-laser annealed Ti/Au contacts to enhance the performance of multilayer MoS2 field effect transistors (FETs) on flexible plastic substrates without thermal damage. An analysis of the temperature distribution, based on finite difference methods, enabled understanding of the compatibility of our picosecond laser annealing for flexible poly(ethylene naphthalate) (PEN) substrates with low thermal budget (< 200 °C). The reduced contact resistance after laser annealing provided a significant improvement in transistor performance including higher peak field-effect mobility (from 24.84 to 44.84 cm2·V−1·s−1), increased output resistance (0.42 MΩ at V gs − V th = 20 V, a three-fold increase), a six-fold increase in the self-gain, and decreased sub-threshold swing. Transmission electron microscopy analysis and current-voltage measurements suggested that the reduced contact resistance resulted from the decrease of Schottky barrier width at the MoS2-metal junction. These results demonstrate that selective contact laser annealing is an attractive technology for fabricating low-resistivity metal-semiconductor junctions, providing important implications for the application of high-performance two-dimensional semiconductor FETs in flexible electronics.