Open AccessInfluence of deposition rate on the structural properties of plasma-enhanced CVD epitaxial silicon
Author(s) -
Wanghua Chen,
Romain Cariou,
Gwénaëlle Hamon,
Ronan Léal,
JeanLuc Maurice,
Pere Roca i Cabarrocas
Publication year - 2017
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/srep43968
Subject(s) - plasma enhanced chemical vapor deposition , silane , epitaxy , materials science , silicon , substrate (aquarium) , deposition (geology) , chemical vapor deposition , hydrogen , amorphous silicon , chemical engineering , crystalline silicon , amorphous solid , layer (electronics) , optoelectronics , nanotechnology , chemistry , composite material , crystallography , organic chemistry , paleontology , oceanography , sediment , geology , engineering , biology
Solar cells based on epitaxial silicon layers as the absorber attract increasing attention because of the potential cost reduction. In this work, we studied the influence of the deposition rate on the structural properties of epitaxial silicon layers produced by plasma-enhanced chemical vapor deposition (epi-PECVD) using silane as a precursor and hydrogen as a carrier gas. We found that the crystalline quality of epi-PECVD layers depends on their thickness and deposition rate. Moreover, increasing the deposition rate may lead to epitaxy breakdown. In that case, we observe the formation of embedded amorphous silicon cones in the epi-PECVD layer. To explain this phenomenon, we develop a model based on the coupling of hydrogen and built-in strain. By optimizing the deposition conditions to avoid epitaxy breakdown, including substrate temperatures and plasma potential, we have been able to synthesize epi-PECVD layers up to a deposition rate of 8.3 Å/s. In such case, we found that the incorporation of hydrogen in the hydrogenated crystalline silicon can reach 4 at. % at a substrate temperature of 350 °C.