Research Projects

Ferroelectric (FE) materials exhibit dual-stability, which is crucial for non-volatile random-access memory or FE field-effect transistors (FEFET). Switching dynamics of FEs are essential parameters for voltage, writing speed, stability, and fatigue of FETs. The MOSFET device has a high drain current ratio, leading to high power dissipation and depending on the Boltzmann distribution energies. The fundamental lower limit is nearly 60 mV/dec, and the Boltzmann limit prevents source voltage from going below 0.5 V. Extrinsic FE (Extrinsic: FE and Dielectric staking) can be replaced with dielectric oxides, potentially overcoming the Boltzmann limit and lowering power reduction. Negative capacitance (NC) phenomena, impending thickness, and Boltzmann limits could improve energy efficiency. FE exhibits multiple polarization states, making it competent for generating NC. Integrating instability and charge dynamics in FE can lead to NC. However, it is challenging to get charges at unstable regions due to Gibbs's free energy diagram. The proposed approach involves recovering the S-shape of polarization dependence on the FE during the slowed transition between two stable states. Switching dynamics of polarization in FE and external electrostatic conditions are limited, but controlling suppressed polarization and electrostatic differences can help achieve NC. NC can be categorized into intrinsic and extrinsic. The first task is to fabricate different libraries of superlattices/epitaxial FE-DE layers, lower the Boltzmann limit, and analyze switching dynamics. Further developing NC in FE/DE will integrate into gate stacks for ultra-low power logic applications.