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Unexpected Large Electrostatic Gating by Pyroelectric Charge Accumulation
Yicheng Mou1, Qi Liu1, Jiaqi Liu1
1State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China.
Nano Letters
|February 27, 2025
Summary
This study demonstrates a novel method for achieving long-term electrostatic gating in graphene devices using the pyroelectric effect of lithium niobate. This voltage-free approach offers a new way to control doping concentrations in electronic components.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Pyroelectricity involves charge accumulation from temperature-induced polarization changes in ferroelectric materials.
- This effect is typically unstable and overlooked in electronic applications like ferroelectric field-effect transistors.
- Graphene's unique electronic properties make it suitable for novel device applications.
Purpose of the Study:
- To investigate the potential of pyroelectricity for achieving stable electrostatic gating in graphene devices.
- To explore the use of a ferroelectric substrate (LiNbO3) and a van der Waals interface (hBN) for enhanced pyroelectric effects.
- To demonstrate a novel, voltage-free gating mechanism with long retention.
Main Methods:
- Utilized a LiNbO3 substrate with pyroelectric properties and a hexagonal boron nitride (hBN) interface.
- Fabricated graphene devices on the LiNbO3/hBN heterostructure.
- Employed transport measurements and noncontact techniques to analyze doping levels and charge accumulation.
Main Results:
- Achieved substantial and long-term electrostatic gating in graphene via the pyroelectric effect of LiNbO3.
- Observed high doping concentrations in graphene, up to 10^13 cm^-2, upon cooling.
- Demonstrated that pyroelectric charge accumulation, enhanced by electric fields, is responsible for the high doping levels.
Conclusions:
- The pyroelectric properties of LiNbO3 can induce significant and persistent doping in graphene through a van der Waals interface.
- This work presents a novel mechanism for voltage-free electrostatic gating with long retention, overcoming previous limitations of the pyroelectric effect.
- The findings open new avenues for developing advanced electronic devices utilizing pyroelectric materials for tunable doping and control.
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