Research

At the heart of my research is the exploration of the Negative Capacitance (NC) effect in both organic and inorganic ferroelectric materials, particularly HfO₂ and P(VDF-TrFE). Traditional MOSFETs face inherent challenges in reducing energy consumption due to 'Boltzmann’s Tyranny,' which limits subthreshold swing to 60 mV/decade. My research overcomes this barrier by utilizing NC effects, enabling lower supply voltages without sacrificing transistor performance.

1. Materials Innovation: I’ve developed device simulations and experimental models for HfO₂ and P(VDF-TrFE), demonstrating how these ferroelectric materials can achieve sub-60 mV/decade operation. This work presents promising results in reducing IC power consumption while maintaining high on-state current and performance levels.

2. Device Applications: My studies encompass the design and testing of ferroelectric-based proof-of-concept devices, such as passive and active voltage amplifiers, steep-slope logic circuits, and mixed-signal applications. Through these designs, we’re paving the way for more efficient digital and analog ICs.

With the rise of artificial intelligence (AI), efficient hardware accelerators for neural network (NN) inference are essential. Current NN accelerators, which rely on multiply-accumulate (MADD) circuits, often compromise on precision to improve speed, resulting in higher energy consumption. My research introduces NCFETs as a potential solution to this trade-off, offering both high accuracy and energy efficiency:

1. Efficiency in NN Inference: NCFETs’ steep-slope properties reduce power requirements for MADD operations, enabling NN accelerators that meet throughput demands without excessive energy costs. This approach enhances accuracy while significantly lowering power consumption, making it ideal for real-time AI applications.

In addition to device-level innovations, my research extends into designing and optimizing digital, analog, and mixed-signal circuits that utilize the unique properties of Negative Capacitance Field-Effect Transistors (NCFETs). By integrating NCFETs into circuit architectures, my work demonstrates substantial improvements in both performance and energy efficiency across a range of applications:

Digital Circuit Design

The sub-60 mV/decade operation of NCFETs addresses the limitations of traditional CMOS technology, enabling digital circuits that operate at lower voltages without sacrificing speed or performance. My work has focused on applying NCFETs to key digital components, such as:

1. Inverters: By leveraging the steep-slope characteristics of NCFETs, I have designed energy-efficient inverters with high switching speeds, ideal for low-power, high-performance computing.

2. Ring Oscillators and Logic Gates: My research includes the development of NCFET-based ring oscillators and logic gates, which exhibit reduced power consumption and increased frequency stability. These components are foundational for high-speed, energy-efficient digital circuits.

Analog Circuit Design

NCFETs’ negative capacitance effect provides a natural voltage amplification capability, which is beneficial in analog applications. My work in this area has led to innovative designs in amplifiers and voltage regulation circuits, which are essential for low-power analog processing:

1. Voltage Amplifiers: I have designed passive voltage amplifiers using NCFETs that achieve stable gain with low power draw. This approach proves especially advantageous in portable and battery-operated devices where energy efficiency is paramount.

2. Differential Amplifiers and Active Filters: By integrating NCFETs, I have developed differential amplifiers and active filters with higher gain-bandwidth products and lower noise profiles, making them suitable for precision analog applications.

Mixed-Signal Circuit Design

NCFET technology also opens new avenues for mixed-signal design, enabling circuits that operate at lower voltages while maintaining signal integrity. Mixed-signal circuits are critical in applications like sensor interfaces, signal processing, and data converters:

1. Analog-to-Digital Converters (ADCs): My research has yielded NCFET-based ADC designs with enhanced linearity and power efficiency. These converters can operate effectively at ultra-low voltages, making them ideal for energy-constrained applications.

2. Digital-to-Analog Converters (DACs): Leveraging the inherent gain characteristics of NCFETs, I have designed DACs with minimal power leakage and improved resolution, suited for mixed-signal systems where high fidelity and low power are required.

3. Clock Generation and Timing Circuits: With the steep-slope advantage of NCFETs, I have created timing circuits that achieve more precise and stable clock signals, facilitating robust mixed-signal designs for high-frequency applications.

Impact and Future Directions

NCFET technology’s unique characteristics enable a unified approach to digital, analog, and mixed-signal circuit design, pushing beyond traditional power and performance limits. This research is not only paving the way for energy-efficient consumer electronics but also supporting the growing demand for high-performance, low-power ICs in IoT devices, AI accelerators, and next-generation wireless communication systems. Future research will focus on scaling these designs and exploring further innovations in NCFET-based circuit architectures, ultimately contributing to the evolution of ultra-low-power electronics.

My long-term research vision involves exploring broader applications for NC beyond transistors. This includes investigating potential breakthroughs in energy storage, supercapacitors, and even 2D superconductivity. I am actively working on three major areas:

1. Fundamental Understanding of HfO₂ Properties: In collaboration with material scientists, I examine the domain configurations in HfO₂-based ferroelectrics. This research aims to deepen our understanding of NC and optimize it for various device applications.

2. Stacked Ferroelectric/Dielectric Capacitors: To achieve stable, ultra-thin ferroelectric layers, my research investigates stacked capacitors using HfO₂ films, focusing on phase stability and energy efficiency.

3. New Device Possibilities Beyond Transistors: I am exploring novel applications of NC, such as ultra-efficient DRAM capacitors, energy-dense supercapacitors, and potential high-temperature superconductivity. These NC applications could transform energy storage and transfer, unlocking new horizons in low-power electronics.