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Efficient n-GaAs photoelectrodes grown by close-spaced vapor transport from a solid source
Andrew J Ritenour1, Richard C Cramer, Solomon Levinrad
1Department of Chemistry and the Materials Science Institute, University of Oregon, University of Oregon, Eugene, Oregon 97403, USA.
ACS Applied Materials & Interfaces
|December 6, 2011
Summary
Close-spaced vapor transport (CSVT) grown n-GaAs films achieved 9.3% solar conversion efficiency, surpassing commercial wafers due to longer carrier diffusion lengths. This highlights potential for scalable gallium arsenide (GaAs) solar energy devices.
Area of Science:
- Materials Science
- Photovoltaics
- Electrochemistry
Background:
- Gallium arsenide (GaAs) is a promising semiconductor for solar energy conversion.
- Optimizing GaAs film growth is crucial for enhancing photoelectrochemical performance.
- Close-spaced vapor transport (CSVT) offers a potential method for scalable GaAs film production.
Purpose of the Study:
- To investigate the photoelectrochemical energy conversion properties of n-GaAs films grown by CSVT.
- To compare the performance of CSVT-grown n-GaAs with commercial n-GaAs wafers.
- To understand the factors limiting and enabling higher conversion efficiencies.
Main Methods:
- Epitaxial growth of n-GaAs films on n(+)-GaAs substrates using the CSVT method.
- Photoelectrochemical characterization under simulated solar illumination (100 mW cm(-2)).
- Measurement of conversion efficiencies and spectral response to determine minority carrier diffusion lengths.
Main Results:
- CSVT n-GaAs photoanodes achieved up to 9.3% conversion efficiency in a ferrocene/ferrocenium test cell.
- This efficiency is significantly higher than the 5.7% measured for commercial n-GaAs wafers.
- CSVT films exhibited longer minority carrier diffusion lengths (up to 1,020 nm) compared to commercial wafers (260 nm).
Conclusions:
- CSVT is a viable method for producing high-performance n-GaAs films for photoelectrochemical energy conversion.
- Extended minority carrier diffusion length is a key factor for improved efficiency in CSVT n-GaAs.
- The findings support the development of scalable and efficient GaAs-based solar energy conversion devices.
