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Origin of the switchable photocurrent direction in BiFeO3 thin films
Yaqiong Wang1,2,3, Matyas Daboczi4,5, Man Zhang2
1Institute of Medical Engineering, Department of Biophysics, School of Basic Medical Sciences, Health Science Centre, Xi'an Jiaotong University, Xi'an, 710061, China.
Materials Horizons
|October 23, 2023
Summary
Switchable photocurrents were observed in bismuth ferrite (BiFeO3) thin films. External bias allows control over anodic and cathodic behavior, enabling applications in optoelectronics.
Area of Science:
- Materials Science
- Solid State Physics
- Photochemistry
Background:
- Bismuth ferrite (BiFeO3) is an indirect band gap perovskite with potential photoactive properties.
- Controlling carrier dynamics in photoactive materials is crucial for advanced electronic devices.
Purpose of the Study:
- To investigate the switchable photocurrent in BiFeO3 thin films.
- To understand the underlying band structure and its influence on photoresponse.
- To demonstrate the control of n-type and p-type behavior via external bias.
Main Methods:
- Fabrication of BiFeO3 photoactive thin films.
- Measurement of external bias-driven photocurrent (anodic and cathodic).
- Ambient photoemission spectroscopy and Kelvin-probe techniques to determine band structure.
- Photochemical determination of flat band potential.
Main Results:
- BiFeO3 films exhibited switchable anodic and cathodic photocurrents.
- The Fermi level was found at -4.96 eV, with a mid-gap at -4.93 eV.
- The flat band potential was determined to be -4.8 eV vs. vacuum.
- External bias enabled switching between n-type and p-type semiconductor behavior.
Conclusions:
- The band positions in BiFeO3 facilitate controllable band bending.
- External bias allows for dynamic control of majority carrier type.
- This control opens applications for optoelectronic switches and energy conversion devices.
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