Nanophase semiconductors embedded within transparent conductive oxides matrices as optical sensitizers for photovoltaic applications

C. G. Allen, G. H. Shih, R. J. Beal, B. G. Potter

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The optical absorption of a transparent conductive oxide (TCO), which is often used as the basis for junction or contact layers in thin film photovoltaics, can be tailored by incorporating a nanophase semiconductor (SC) component. Using a, dual-source, sequential R.F. magnetron sputter deposition technique, we manipulate the optical and electronic properties of SC:TCO composites by varying the local and extended nanophase assembly and composition. The present study explores nanocomposite systems based on Ge:ZnO and Ge:ITO. The impact of host material (ITO vs. ZnO) on the evolution of nanostructure is investigated. Heat treatment of the as-deposited films results in an increased crystallinity of the TCO and SC components, confirmed by X-ray diffraction and Raman spectroscopy studies. The presence of the SC phase is found to influence TCO grain growth and crystallographic orientation, and modification of the SC phase distribution is coincident with the morphological development of the TCO phase in both composite systems. Upon heattreatment, the high-energy optical absorption edge of the nanocomposite is blue-shifted compared to that of the corresponding as-deposited material. This indicates the development of quantum-confinement conditions for photocarriers within the Ge phase which leads to an increased energy gap over that expected for the more bulk-like, asdeposited Ge material. Under the deposition and thermal treatment conditions used in the present study, the spectral absorption response is consistent between the ZnO and ITO-based thin films examined. This suggests that carrier confinement conditions are mediated by the development of similar Ge-phase local spatial extent and Ge:TCO interfacial structures in both systems, regardless of TCO identity.

Original languageEnglish (US)
Title of host publicationNext Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion
DOIs
StatePublished - Oct 18 2010
EventNext Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion - San Diego, CA, United States
Duration: Aug 1 2010Aug 4 2010

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume7772
ISSN (Print)0277-786X

Other

OtherNext Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion
CountryUnited States
CitySan Diego, CA
Period8/1/108/4/10

Keywords

  • Nanocomposite
  • Quantum-confined semiconductor
  • Thin-film
  • Transparent conductive oxides

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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  • Cite this

    Allen, C. G., Shih, G. H., Beal, R. J., & Potter, B. G. (2010). Nanophase semiconductors embedded within transparent conductive oxides matrices as optical sensitizers for photovoltaic applications. In Next Generation (Nano) Photonic and Cell Technologies for Solar Energy Conversion [77721L] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 7772). https://doi.org/10.1117/12.859875