Prof. Pere Roca i Cabarrocas, 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. From 2012 to 2020 he was the director of LPICM and of the French PV Federation. He is currently the scientific director of IPVF. 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, etc. More recently he has been applying silicon nanocrystals synthesized in the plasma as building blocks 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. 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. Since 2016 he is invited professor at Nara Institute of Technology and scientific director of IPVF since 2019. He has over 520 papers, holds 38 patents and has supervised 56 PhD students.

Nano-engineered crystalline silicon materials and nanostructures via low temperature plasma processes



Pere Roca i Cabarrocas


Silicon thin film technology has been driven by hydrogenated amorphous and microcrystalline silicon thin films which are routinely produced using silane plasmas. The dissociation of silane gas molecules results in a wide variety of film precursors, ranging from SiHx radicals to ions and clusters. While SiH3 is often considered to be the main radical for the obtaining of such films, we have shown that changing the process to conditions where silicon clusters and nanocrystals are produced in the plasma can lead to high deposition rates and materials with improved electronic properties, such as hydrogenated polymorphous silicon and polycrystalline silicon [1]. Moreover, by changing the substrate from glass to crystalline silicon and the film precursors from SiHx radicals to silicon clusters, it is possible to produce epitaxial silicon films developing a fragile (porous) interface layer, which favors their transfer to foreign substrates to make ultrathin crystalline silicon solar cells [2]. Even more interesting, this low temperature epitaxial process can be extended to doped films as well as to germanium and SiGe alloys and their heteroepitaxial growth on GaAs [3], thus providing an easy route for the integration of c-Si and III-V materials. Last but not least, combining PECVD with low melting temperature metal nanoparticles such as indium and tin, opens the way to the growth of nanowires (including Ge, Si and GeSn), which allow to achieve efficient light trapping and carrier collection in radial junction solar cells on flexible and light weight substrates [4] or even to growth in-plane c-Si nanowires for stretchable electronics and photonics applications [5], where the high internal energy of a-Si:H as well as its controllable surface energy via hydrogen termination [6] are key parameters governing the growth process. The different aspects of the plasma and plasma/surface interaction will be discussed in view of the fabrication of nano-engineered materials.



[1] Ka-Hyun Kim Sci. Reports 7, (2017) 40553.

[2] R. Cariou et. al. Prog. in Phot.: Research and Applications 24 (2016) 1075-1084.

[3] Gwenaëlle Hamon, J. Photon. Energy 7 (2017) 022504.

[4] X. Sun, Nano Energy 53 (2018) 83-90.

[5] Ying Sun  et. al. Adv. Mater. (2019) 1903945.

[6] Zhaoguo Xue, Applied Surface Science 593 (2022) 153435 


Plenary Speaker


Pere Roca i Cabarrocas

LPICM-CNRS, Ecole polytechnique, Institut Polytechnique de Paris, France

Plenary (17:10-17:50, 26th Aug, Zijin Lecture Hall (紫金报告厅))



LPICM-CNRS, Ecole polytechnique, Institut Polytechnique de Paris, France


Route de Saclay, 91128 Palaiseau, Cedex






Plenary: Pere Roca i Cabarrocas