Enhancing Electrical Performance of 2D Semiconductor Tungsten Diselenide (WSe₂)—Metal Junctions for Sustainable Electronics Through Hydrochloric Acid Surface Modification

The performance of silicon-based integrated circuits has continuously advanced in accordance with Moore's Law, driven by technological innovations such as EUV HVM and GAAFET to address emerging challenges. However, applications like big data and IoT demand greater performance and efficiency, aligning with the More-Moore approach. To overcome chip performance degradation due to physical limitations in sub-1nm technology nodes, 2D transition metal dichalcogenides (TMD) materials are emerging as promising next-generation channel materials, particularly for sustainable electronics. These materials offer the potential for reduced energy consumption and enhanced performance. However, integrating 2D TMDs as channel materials presents challenges, especially in achieving low resistance at semiconductor-metal junctions. The high Schottky barrier height caused by Fermi level pinning results in increased contact resistance, which can impede overall efficiency. Addressing these challenges is crucial for developing sustainable electronic devices that minimize environmental impact while maximizing performance. In this study, we addressed the Fermi level pinning effect by treating specific areas of bilayer WSe₂, where the metal electrode contacts, with hydrochloric (HCl) solution. This approach not only improved the electrical properties but also contributes to the sustainability of electronic devices by enhancing their efficiency. We experimentally confirmed that HCl-treated samples exhibited superior n-FET and p-FET transfer characteristics compared to pristine samples. Specifically, the on current for p-FET increased from 53.4 to 111.8 μA/μm, while for n-FET, it rose from 5.66 to 11.35 μA/μm. The reduction in Schottky barrier height was validated through low-temperature measurements and Richardson plots. We propose that the observed improvements in electrical properties stem from the alleviation of Fermi level pinning rather than a doping effect from HCl treatment. This method enhances the performance of 2D TMD materials, making them more viable for sustainable electronics applications that prioritize energy efficiency and performance.