Silane plasmas: a wonderful toolbox for the synthesis of nanomaterials


Event details

Date and time 19.10.2015 13:1514:15  
Place and room
Speaker Prof. Pere Roca i Cabarrocas, LPICM CNRS Ecole Polytechnique, Palaiseau France
Category Conferences - Seminars
Crystalline silicon, epitaxial growth. What are the required process conditions? Do you need high temperature? Is ultrahigh vacuum required?
What about disordered materials? You may know that hydrogenated amorphous and microcrystalline silicon thin films are routinely produced using silane plasmas at low temperature (~200 °C). But what are the details of the growth process? While SiH3 is often considered as the main radical for the obtaining of such films, we will see that moving the process to conditions where silicon clusters and nanocrystals are produced in the plasma can lead to high deposition rates and improved materials, such as hydrogenated polymorphous silicon and polycrystalline silicon. Moreover, by changing the substrate from glass to crystalline silicon, it is possible to produce epitaxial thin crystalline silicon films which can be transferred to foreign substrates for flexible electronic devices [1]. Even more interesting, this low temperature epitaxial process can be extended to germanium and to SiGe alloys on c-Si but also on GaAs [2]. Last but not least, combining PECVD with low melting temperature metal particles such as indium and tin opens the way to the growth of silicon nanowires, which allow achieving efficient light trapping and carrier collection in radial junction solar cells [3] or even to grow in-plane nanowires [4].

1. M. Moreno and P. Roca i Cabarrocas. EPJ Photovoltaics 1, (2010) 10301.
2. R. Cariou, J. Tang, N. Ramay, R. Ruggeri, and P. Roca i Cabarrocas. Solar Energy Materials and Solar Cells 134 (2015) 15.
3. S. Misra, L. Yu, M. Foldyna, and P. Roca i Cabarrocas. Solar Energy Materials and Solar Cells 118 (2013) 90.
4. L. Yu, M. Xu, J. Xu, Z. Xue, Z. Fan, G. Picardi, F. Fortuna, J. Wang, J. Xu, Y. Shi, K. Chen and P. Roca i Cabarrocas. Nano Letters 14 (2014)6469.

Bio: Prof. Pere Roca i Cabarrocas, native of Catalonia, is an Electrical Engineer from the “Universitat Politécnica de Barcelona”. In 1984 he moved to Paris, where he received his PhD from University Paris VII in 1988. After a post-doc position in Princeton University he joined the Laboratory of Physics of Interfaces and Thin Films at Ecole Polytechnique where he holds a position as a CNRS director of research and as a professor. Since 2012 he is the director of LPICM. He has thirty years of experience in the field of plasma deposition of silicon based thin films for large area electronic applications His topics cover the study of RF discharges for the deposition of amorphous, polymorphous and microcrystalline silicon thin films. He has used in-situ diagnostic techniques such as UV-visible ellipsometry, Kelvin probe and time resolved microwave conductivity to understand the growth of these materials and apply them to the production of devices such as solar cells, thin film transistors, particle detectors, sensors,… More recently he has been applying silicon nanocrystals synthesized in the plasma as building blocs for the epitaxial growth of silicon thin films and Si/Ge quantum wells. On the other hand, he has extended the plasma processes to the growth of vertical silicon nanowires for third generation solar cells and of horizontal ones for planar electronic applications; both types of wires being achieved at low temperature and in a single pump down process. He was the recipient of the Médaille Blondel in 2004, of the Innovation Award at Ecole Polytechnique in 2009 and the Silver medal from CNRS in 2011. He has over 380 papers in peer reviewed journals and holds 31 patents.

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  • General public
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  • Michele Ceriotti


  • Michele Ceriotti

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