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Selective Oxidation and Carbonization by Laser Writing into Porous Silicon
Author(s) -
Keating Adrian,
Sun Xiao
Publication year - 2019
Publication title -
advanced materials technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.184
H-Index - 42
ISSN - 2365-709X
DOI - 10.1002/admt.201800334
Subject(s) - carbonization , materials science , raman spectroscopy , porous silicon , chemical engineering , silicon , hydrofluoric acid , propane , porosity , carbon fibers , composite material , scanning electron microscope , optoelectronics , organic chemistry , optics , chemistry , metallurgy , physics , composite number , engineering
The selective formation of either oxidized or carbonized features into 2.5 µm thick porous silicon (PS) films using laser writing at a wavelength of 405 nm is demonstrated. Oxidized features are formed in air while carbonized features are achieved during the flow of propane at 600 sccm. Voids which have been previously associated with the use of propane are not observed, largely due to the rapid heating and high flow rates achieved in the experiment. Carbonized regions with feature widths down to 1.8 µm are achieved and chemical resistance to both hydrofluoric acid and potassium hydroxide is demonstrated. Once carbonized regions are formed, the surrounding areas can be overwritten in air to convert the surrounding regions into oxidized PS allowing films to be created with as‐fabricated, oxidized and carbonized regions. Energy dispersive X‐ray and Raman analysis confirms the presence of carbon within the written structures. At high optical powers, cracking around the carbonized features is observed which is attributed to a contraction of the film. Such cracking is not observed during selective oxidation of features. This work significantly enhances the ability to engineer and pattern the composition of PS films enabling selective control of the material's properties and functionality.