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Multi-Domain Negative Capacitance Effects in Metal-Ferroelectric-Insulator-Semiconductor/Metal Stacks: A Phase-field
Atanu K Saha1, Sumeet K Gupta2
1School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA. saha26@purdue.edu.
Scientific Reports
|June 25, 2020
Summary
Domain walls in ferroelectric materials create a negative capacitance effect, enhancing charge response in Metal-Ferroelectric-Insulator-Metal and Metal-Ferroelectric-Insulator-Semiconductor stacks. This effect depends on material properties, not intrinsic ferroelectric behavior.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Semiconductor Device Physics
Background:
- Negative capacitance (NC) effect in ferroelectric materials is a key area for advanced electronic devices.
- Understanding ferroelectric domain wall dynamics is crucial for harnessing NC effects.
- Metal-Ferroelectric-Insulator-Metal (MFIM) and Metal-Ferroelectric-Insulator-Semiconductor (MFIS) structures are promising for novel device applications.
Purpose of the Study:
- To analyze the ferroelectric domain-wall induced negative capacitance (NC) effect in MFIM and MFIS stacks.
- To investigate the influence of ferroelectric properties and stack structure on NC behavior.
- To explore the charge and potential distribution within these stacks under applied voltage.
Main Methods:
- Phase-field simulations were employed to model the ferroelectric behavior.
- Self-consistent solving of the time-dependent Ginzburg-Landau equation, Poisson's equation, and semiconductor charge equations.
- Analysis of 180° ferroelectric domain formation and polarization switching characteristics in Hf0.5Zr0.5O2 based stacks.
Main Results:
- Applied voltage-induced polarization switching via domain-wall displacement showed non-hysteretic characteristics.
- Domain-wall displacement led to a non-homogeneous effective local negative permittivity, enhancing charge response in MFIM compared to Metal-Insulator-Metal.
- The NC effect was found to be dependent on ferroelectric thickness and material properties, not intrinsic to the ferroelectric itself.
- MFIS stacks exhibited enhanced charge/capacitance compared to Metal-Oxide-Semiconductor (MOS) capacitors, with non-homogeneous potential distributions.
- Co-existence of electrons and holes was observed in undoped semiconductors at low voltages due to potential non-homogeneity.
Conclusions:
- Ferroelectric domain walls induce a significant negative capacitance effect, leading to enhanced charge response in MFIM and MFIS devices.
- The NC effect's magnitude and characteristics are tunable through material properties and device architecture.
- The study provides insights into the complex interplay of ferroelectricity, domain dynamics, and semiconductor behavior in advanced electronic structures.
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