Realization of low-power and high mobility thin film transistors based on MoS2 layers grown by PLD technique

Abstract

Molybdenum disulfide (MoS2) layers have been successfully grown and optimized for the realization of low power thin film transistors (TFTs) using catalysis free, economical and environment-friendly pulsed laser deposition (PLD) technique on comparably large sized passivated silicon (SiO2/Si) substrate of area 1.2 cm×1.0 cm. Growth of MoS2 monolayer is confirmed by reflection high-energy electron diffraction (RHEED), Raman spectroscopy, photoluminescence (PL) analysis and atomic force microscopy (AFM). The effect of planar electrodes of different metal system (Au/Ag, Pt/Ti, Al, Ni) on the electrical characteristics of MoS2 layers have been inspected in detail. Au/Ag bilayer system proved to be the best electrode for efficient charge injection into the MoS2 layers. A Back-gated field effect transistor (FET) was fabricated with Au/Ag was used as source-drain contacts and MoS2 as the semiconducting channel has been successfully developed. The fabricated transistor shows an accumulation electron mobility around 44.6 cm2 V-1s−1, current ION/OFF ratio of 1.4×105, subthreshold slope of nearly 360 mV/dec, interface trap density of 1.18×1012 /cm2eV and robust current saturation at lower Vds, suggesting that fabricated devices can be used in making low power switching devices.