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Published on: November 29, 2016
The surface-state-induced Stark effect in ZnO nanocrystals
Jianpu Wang1, Feng Gao, Toby Hallam
1Cavendish Laboratory, J J Thomson Avenue, Cambridge CB3 0HE, UK.
Summary
UV light alters electrical properties of zinc oxide (ZnO) nanoparticles by changing surface states. This study links optical absorption changes to electric field variations, revealing a Stark effect mechanism in ZnO nanocrystal films.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Physics
Background:
- Surface states in zinc oxide (ZnO) nanoparticles significantly influence electrical transport.
- These electrical properties are highly sensitive to ultraviolet (UV) light exposure.
Purpose of the Study:
- To investigate the origin of UV light-induced modifications in ZnO nanoparticle electrical properties.
- To correlate changes in optical absorption with surface state alterations under UV illumination.
Main Methods:
- Fabrication of ZnO nanoparticle films.
- Optical absorption spectroscopy to analyze spectral changes.
- Annealing studies to observe spectral evolution.
- UV illumination experiments.
- Electrostatic Force Microscopy (EFM) to probe electric fields.
Main Results:
- Annealing ZnO nanoparticle films modifies the modulation spectrum from a first to a second derivative of the absorption spectrum.
- UV illumination alters the surface states of ZnO nanocrystals.
- A change in the electric field within the films was detected using EFM.
- Optical absorption modulation is consistent with a Stark effect.
Conclusions:
- UV light induces changes in ZnO nanoparticle surface states, affecting the internal electric field.
- The observed optical absorption modulation is attributed to a UV-induced Stark effect in ZnO nanocrystals.
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