HfZrO₂-Based Negative Capacitance Field-Effect Transistor with Molybdenum Disulfide Transition Metal Dichalcogenides and Al₂O₃ Dielectrics

Subthreshold swing (SS) of conventional metal-oxide-semiconductor field-effect transistors (MOSFETs) have been limited to the 60 mV/dec by the fundamental thermionic limitation, so called Boltzmann tyranny. To overcome the limitation, The negative capacitance (NC) field effect transistor using thin film of doped HfO₂-based ferroelectrics has been attracting attentions due to the compatibility of CMOS process, maintaining ferroelectricity under 10 nm thickness, high retention and endurance.^[1-3] In addition, Molybdenum disulfide (MoS₂) of transition metal dichalcogenides has been extensively studied for low-power and high performance transistors as channel layer due to high carrier mobility, thickness dependence of band structure and no surface roughness.^[4-6]<br/>Here, we fabricated a ferroelectric field effect transistor (Fe-FET) using a HfZrO₂ ferroelectric as a gate dielectric and a CVD-grown monolayer MoS₂ as a channel layer. It was directly observed that the drain current changed rapidly in the region where the polarization is switched from I_g-V_g, and the I_on/I_off ratio and the subthreshold swing were observed to change according to the amount of polarization switching. In addition, we fabricated the negative capacitance field effect transistor using the series of HfZrO₂ and Al₂O₃ as a gate dielectric. It showed over 10⁷ I_on/I_off ratio and less than 60 mV/dec subthreshold swing without hysteresis behavior at the low voltage driving (1 V_g).<br/><b>Reference</b><br/>1. Min Hyuk Park et al. MRS communications. 8, 3, (2018)<br/>2. Sayeef Salahuddin and Supriyo Datta. Nano Lett. 8, 2, 405-410 (2008)<br/>3. Mengwei Si, et al. Nature Nanotechnology 13, 24-28 (2018)<br/>4. Radisavljevic, B et al, Nature Nanotech. 6, 147-150 (2011)<br/>5. Mak, K et al. Phys. Rev. Lett. 105, 136805 (2010)<br/>6. Li, S.-L et al. Nano Lett. 13 (8), 3546-3552 (2013)<br/><b>Acknowledgments</b><br/>This research was supported by the Industrial Strategic Technology Development Program (20006492) funded by the Ministry of Trade, Industry and Energy (MOTIE, Korea).