Opto-electronic properties of co-deposited mixed-phase hydrogenated amorphous/nanocrystalline silicon thin films

James Kakalios, U. Kortshagen, C. Blackwell, C. Anderson, Y. Adjallah, L. R. Wienkes, K. Bodurtha, J. Trask

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


Mixed-phase thin film materials, consisting of nanocrystalline semiconductors embedded within a bulk semiconductor or insulator, have been synthesized in a dual-chamber co-deposition system. A flow-through plasma reactor is employed to generate nanocrystalline particles, that are then injected into a second, capacitively-coupled plasma deposition system in which the surrounding semiconductor or insulating material is deposited. Raman spectroscopy, X-ray diffraction and high resolution TEM confirm the presence of nanocrystals homogenously embedded throughout the a-Si:H matrix. In undoped nc-Si within a-Si:H (a/nc-Si:H), the dark conductivity increases with crystal fraction, with the largest enhancement of several orders of magnitude observed when the nanocrystalline density corresponds to a crystalline fraction of 2-4%. These results are consistent with the nc donating electrons to the surrounding a-Si:H matrix without a corresponding increase in dangling bond density for these films. In contrast, charge transport in n-type doped a/nc-Si:H films is consistent with multi-phonon hopping, possibly through extended nanocrystallite clusters with weak electron-phonon coupling. The flexibility of the dual-chamber co-deposition process is demonstrated by the synthesis of mixed-phase thin films comprised of two distinct chemical species, such as germanium nanocrystallites embedded in a-Si:H and Si nanocrystallites embedded within an insulating a-SiN x:H film.

Original languageEnglish (US)
Title of host publicationAmorphous and Polycrystalline Thin-Film Silicon Science and Technology - 2011
Number of pages12
StatePublished - 2012
Event2011 MRS Spring Meeting - San Francisco, CA, United States
Duration: Apr 25 2011Apr 29 2011

Publication series

NameMaterials Research Society Symposium Proceedings
ISSN (Print)0272-9172


Other2011 MRS Spring Meeting
Country/TerritoryUnited States
CitySan Francisco, CA

Bibliographical note

Funding Information:
The assistance of C. R. Perrey, J. Deneen and C. Barry Carter with high-resolution TEM imaging is gratefully acknowledged, as are insightful conversations with B. I. Shklovskii and P. Stradins. This work was partially supported by NSF grants NER-DMI-0403887, DMR-0705675, IGERT grant DGE-0114372, in part by the MRSEC Program of the NSF-DMR-0212302, NSF grant DMR-0705675, the NINN Characterization Facility, the Xcel Energy grant under RDF contract #RD3-25, NREL Sub-Contract XEA-9-99012-01 and the University of Minnesota.


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