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Influence of the doping level on the microstructure of P ‐type porous silicon studied by small‐angle X‐ray scattering
Author(s) -
Vezin V.,
Goudeau Ph.,
Naudon A.,
Herino A.,
Bomchil G.
Publication year - 1991
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889891001085
Subject(s) - small angle x ray scattering , materials science , microstructure , silicon , porous silicon , scattering , doping , wafer , porosity , small angle scattering , dopant , composite material , crystallography , optics , nanotechnology , optoelectronics , chemistry , physics
Small‐angle scattering of X‐rays (SAXS) can lead to a better understanding of the microstructure of porous silicon because the pore radii range (2–10 nm) corresponds to the small‐angle scattering investigation range (1–100 nm). A recent SAXS study performed by some of the present authors on porous layers prepared on lightly doped and heavily doped silicon wafers revealed strong differences according to the dopant type. Here the dependence of the microstructure of P ‐type porous silicon on its doping level is focused upon. In nondegenerate P ‐type silicon, the porous structure is an apparently random distribution of voids. The scattering pattern obtained in that case is isotropic. In degenerately doped P ‐type silicon ( P + ), the porous film structure consists of many long voids running perpendicular to the surface, with small `buds' on their sides. SAXS experiments carried out with a two‐dimensional detector revealed the anisotropic character of the P + microstructure.