Nanoassembly control and optical absorption in CdTe-ZnO nanocomposite thin films

Journal Article · Wed Feb 01 00:00:00 EST 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3679081· OSTI ID:22038857

Potter, Jr, B G ^[1]; Beal, R J; Allen, C G ^[1]

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1. Materials Science and Engineering Department, University of Arizona, Tucson, Arizona 85721 (United States)

The spatial distribution of CdTe nanoparticles within a ZnO thin-film matrix was manipulated using a dual-source, sequential radio-frequency (RF)-sputter deposition technique to produce nanocomposite materials with tuned spectral absorption characteristics. The relative substrate exposure time to each sputtering source was used to control the semiconductor phase connectivity, both within the film plane and along the film growth direction, to influence the degree of photocarrier confinement and the resulting optical transition energies exhibited by the CdTe phase. Significant changes (up to {Delta}E {approx_equal} 0.3 eV) in the absorption onset energy for the CdTe nanoparticle ensemble were produced through modification in the extended structure of the semiconductor phase. Raman spectroscopy, cross-sectional transmission electron microscopy, and x-ray diffraction were used to confirm the phase identity of the CdTe and ZnO and to characterize the nanostructures produced in these composite films. Isochronal annealing for 5 min at temperatures up to 800 deg. C further indicated the potential to improve film crystallinity as well as to establish the post-deposition thermal processing limits of stability for the semiconductor phase. The study highlights the significance of ensemble behavior as a means to influence quantum-scale semiconductor optical characteristics of import to the use of such materials as the basis for a variety of optoelectronic devices, including photosensitized heterojunction components in thin film photovoltaics.

• OSTI ID: 22038857
• Journal Information: Journal of Applied Physics, Vol. 111, Issue 3; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
36 MATERIALS SCIENCE
ANNEALING
CADMIUM TELLURIDES
COMPOSITE MATERIALS
EV RANGE
HETEROJUNCTIONS
NANOSTRUCTURES
PARTICLES
PHASE STABILITY
PHOTOVOLTAIC EFFECT
RAMAN SPECTRA
RAMAN SPECTROSCOPY
SEMICONDUCTOR MATERIALS
SPATIAL DISTRIBUTION
SUBSTRATES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
ZINC OXIDES