Quantum confinement in mixed phase silicon thin films grown by co-deposition plasma processing

J. D. Fields, S. McMurray, L. R. Wienkes, J. Trask, C. Anderson, P. L. Miller, B. J. Simonds, J. Kakalios, U. Kortshagen, M. T. Lusk, R. T. Collins, P. C. Taylor

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9 Scopus citations


Mixed phase, hydrogenated amorphous and nanocrystalline silicon thin films grown by co-deposition (nanocrystals and amorphous material deposited sequentially in the same vacuum system) demonstrate pronounced quantum confinement effects. Based on photoluminescence measurements of co-deposited samples, we find evidence that the optical gap of nanocrystals embedded in hydrogenated amorphous silicon is increased to energies exceeding bulk crystalline silicon values - at least as high as 1.35 eV. The broad spectrum of emission of the nanocrystals is attributed to the size distribution and local fluctuations in matrix hydrogenation. The temperature dependence of this PL suggests that these nanocrystals possess fewer defects than those grown by conventional plasma enhanced chemical vapor deposition methods. Interactions between electronic states in nanocrystals and localized states in amorphous silicon matrix tissues are discussed in terms of their role in determining the strength of the quantum confinement potential.

Original languageEnglish (US)
Pages (from-to)7-12
Number of pages6
JournalSolar Energy Materials and Solar Cells
StatePublished - Oct 2014

Bibliographical note

Funding Information:
This work acknowledges primary funding through the Center for Advanced Solar Photophysics, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, and Office of Basic Energy Sciences (BES) . Authors M.T. Lusk, R.T Collins, and P.C. Taylor acknowledge funding through the Renewable Energy MRSEC at Colorado School of Mines, under NSF Contract no. DMR 0820518 , and funding under DOE SunShot award DE-EE0005326 . The University of Minnesota authors acknowledge support by NSF Grant DMR-0705675 , an Xcel Energy Grant under RDF Contract no. #RD3-25 , the NINN Characterization Facility and the Nanofabrication Center . Finally, we thank our colleagues at United Solar Ovonics, Inc., for a long standing collaboration in synthesis and characterization activities concerning a/nc-Si:H materials. Finally, the authors are pleased to dedicate this work to the memory of Professor J. David Cohen whose many important contributions to our understanding of defects in semiconductors are both significant and lasting.


  • Nanocrystalline silicon
  • Nanostructures
  • Photoluminescence
  • Photovoltaics
  • Quantum confinement


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