Fabrication and Characterization of Two-Dimensional Field Effect Transistors based on Hafnium Disulfide

Abstract Two-dimensional field effect transistors based on transition metal dichalcogenides are emerging as promising candidates for post-silicon nanoelectronics. Hafnium disulfide (HfS₂) offers superior dielectric properties, enhanced environmental stability, and reduced electron-phonon coupling compared to the widely studied molybdenum disulfide (MoS₂). This work presents the fabrication and characterization of HfS₂-based FETs. The detailed substrate preparation, plasma oxidation, mechanical exfoliation, dry transfer, and nanoscale electrode patterning via electron beam lithography are discussed. Electrical characterization, including four-probe transport and temperature-dependent analyses, reveals key transport mechanisms and performance limitations.The device exhibits typical n-type behavior, with a well-defined threshold voltage of ~1.4 V, an on-state drain current exceeding 100 µA, and an off-state drain current in the femtoampere range, resulting in an Ion/Ioff ratio above 10⁶. Output characteristics show clear drain current saturation at a drain voltage %VD higher than 1.8 V, confirming good electrostatic control and low contact resistance. The transfer characteristics are consistent across multiple sweeps and configurations, demonstrating the reproducibility and stability of the device, highlighting the potential of HfS₂ for high-performance 2D electronics. A comparative study with MoS₂-based devices underscores the advantages and current challenges of HfS₂, highlighting its potential for next generation low-power flexible electronics. In addition, we discuss emerging opportunities for hybrid architectures and advanced applications, paving the way for innovative uses beyond conventional transistor technologies.