Evolution of silicon bulk lifetime during III–V‐on‐Si multijunction solar cell epitaxial growth
- Instituto de Energía Solar Universidad Politécnica de Madrid, ETSI Telecomunicación Madrid Spain
- Institute for Materials Research The Ohio State University Columbus OH USA
- Department of Electrical &, Computer Engineering The Ohio State University Columbus OH USA
- Área de Tecnología Electrónica Universidad Rey Juan Carlos Móstoles Madrid 28933 Spain
- Institute for Materials Research The Ohio State University Columbus OH USA, Department of Electrical &, Computer Engineering The Ohio State University Columbus OH USA
Abstract The evolution of Si bulk minority carrier lifetime during the heteroepitaxial growth of III–V on Si multijunction solar cell structures via metal‐organic chemical vapor deposition (MOCVD) has been analyzed. In particular, the impact on Si lifetime resulting from the four distinct phases within the overall MOCVD‐based III–V/Si growth process were studied: (1) the Si homoepitaxial emitter/cap layer; (2) GaP heteroepitaxial nucleation; (3) bulk GaP film growth; and (4) thick GaAs y P 1‐y compositionally graded metamorphic buffer growth. During Phase 1 (Si homoepitaxy), an approximately two order of magnitude reduction in the Si minority carrier lifetime was observed, from about 450 to ≤1 µs. However, following the GaP nucleation (Phase 2) and thicker film (Phase 3) growths, the lifetime was found to increase by about an order of magnitude. The thick GaAs y P 1‐y graded buffer was then found to provide further recovery back to around the initial starting value. The most likely general mechanism behind the observed lifetime evolution is as follows: lifetime degradation during Si homoepitaxy because of the formation of thermally induced defects within the Si bulk, with subsequent lifetime recovery due to passivation by fast‐diffusing atomic hydrogen coming from precursor pyrolysis, especially the group‐V hydrides (PH 3 , AsH 3 ), during the III–V growth. These results indicate that the MOCVD growth methodology used to create these target III–V/Si solar cell structures has a substantial and dynamic impact on the minority carrier lifetime within the Si substrate. Copyright © 2015 John Wiley & Sons, Ltd.
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- DE‐EE0005398
- OSTI ID:
- 1401168
- Journal Information:
- Progress in Photovoltaics, Journal Name: Progress in Photovoltaics Vol. 24 Journal Issue: 5; ISSN 1062-7995
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- United Kingdom
- Language:
- English
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