Selective and local flash-annealing for improvement in the contact characteristics of MoS₂ transistors

The fields of nanoscience and nanotechnology have recently progressed toward the sub-10 nm scale, which is a technology node that requires new materials for various applications owing to the quantum mechanical limitations of silicon. Accordingly, two-dimensional transition-metal dichalcogenides (2D TMDCs) are widely being studied due to their great potential for low-power electronics. Despite these striking advantages, 2D TMDC field-effect transistors have poor mobility due to their high contact resistance and interfacial scattering of defects. To mitigate non-ideal electrical contacts, thermal annealing processes are performed in most cases; however, such processes require expensive and bulky equipment. In this study, a facile approach is proposed for ambient-air and selective annealing, which is performed on a wafer scale between MoS₂ and electrodes through flash lamp irradiation. Flash lamp irradiation promotes excellent photothermal annealing, thus increasing the electrode temperature to >640 K, significantly enhancing the device performance. It was confirmed that the primary cause for the improvement of contact characteristics is the hybridization between Au and MoS₂ and the generation of sulfur vacancies in MoS₂, supported by surface element analysis and optical measurements.