A parametric study of laser induced ablation–oxidation on porous silicon surfaces

Abstract

We have investigated the laser induced ablation-oxidation process on porous silicon layers having different porosities and thicknesses by non-destructive optical techniques. In particular, the interaction between a low power blue light laser and the porous silicon surfaces has been characterized by variable angle spectroscopic ellipsometry and Fourier transform infrared spectroscopy. The oxidation profiles etched on the porous samples can be tuned as functions of the layer porosity and laser fluence. Oxide stripes of width less than 2 µm and with thicknesses between 100 nm and 5 µm have been produced, depending on the porosity of the porous silicon, by using a 40 × focusing objective.

Ultraviolet laser patterning of porous silicon

“…While the first one consists of microstructuring the crystalline silicon (c-Si) substrate with the desired pattern followed by porosification, 17 the second and most widely applied method consists of creating the pattern directly on the nanoPS layer by using a diversity of tools such as dry soft lithography, 20 stamp pressing, 19 or laser writing. 10,21 However, none of these methods have the capability to offer flexibility in the pattern design in a timeefficient process, in large areas and in a single-step process. A more versatile approach that has the potential for meeting these requirements is laser interferometry.…”

Submicron machining and biomolecule immobilization on porous silicon by electron beam

“…These kinds of processes can be locally further stressed and speeded up by using different techniques, such as laser writing [15,16] or contact atomic force microscopy-based methods [17]. From this point of view, EBL can potentially be used to remove material from a solid substrate only in submicrometer-wide regions due to the high focusing power of the electron beam.…”

Optical sensing of chemicals by a porous silicon Bragg grating waveguide

“…In Figure The morphological characteristics of the grating can be differently set by choosing proper porosities of the waveguide layers because the width and the depth of the laser oxidized regions depend both on the laser fluence and on the PSi porosity as can be found elsewhere [9] . We have used the transfer matrix method and the slab waveguide modal calculation, obtained by m-line measurements, to calculate the transmission spectrum of the resonant structure.…”