Nanoscale Devices Based on Two-dimensional Materials and Ferroelectric Materials

In this paper, we review our research on nanoscale electronic and optoelectronic devices based on two-dimensional (2D) materials and ferroelectric materials. Our study reveals that the current transport in graphene is highly influenced by the number of layers, local topography, and gate dielectrics on the graphene. High-performance radio-frequency (RF) devices and plasmonic photodetectors were fabricated based on graphene. We also synthesized monolayer molybdenum disulfide (MoS
₂
) and tungsten diselenide (WSe
₂
) using chemical vapor deposition. The domain size of monolayer WSe
₂
exceeds 100 μm. We demonstrate that logic devices based on MoS
₂
have the potential to suppress short-channel effects and have high critical breakdown electric field. The gap states of MoS
₂
were characterized using ac conductance. We found that the true band mobility of MoS
₂
is much higher than the measured effective mobility due to the large number of gap states. In addition, we systematically investigated ferroelectric aluminum (Al)-doped hafnium oxide (HfO
₂
) with various top electrodes, Hf to Al ratios, and annealing temperatures. High-quality ferroelectric Al-doped HfO
₂
with high remanent polarization and long endurance have been demonstrated.