Optical transmission and laser structuring of silicon membranes

Abstract

Abstract:The optical linear and nonlinear properties of ∼ 340-nmthick Si membranes were investigated. The investigation included both experiments in which the reflection and transmission from the membranes were measured, and finite differences time domain simulations. The linear optical transmission of the Si membranes can be controlled by changing the thickness of a thermally grown oxide on the membrane. Illumination of the membranes with high levels of irradiation leads to optical modifications that are consistent with the formation of amorphous silicon and dielectric breakdown. When irradiated under conditions where dielectric breakdown occurs, the membranes can be ablated in a well-controlled manner. Laser micro-structuring of the membranes by ablation was carried out to make micrometer-sized holes by focused fs-pulses. Ns-pulses were also used to fabricate arrays of holes by proximity-ablation of a closely-packed pattern of colloidal particles.

Optically-Thin Broadband Graphene-Membrane Photodetector

“…For around λ = 1 µm (the thickness of the Si 3 N 4 membrane d = 2 µm), the expected value of the absorbtion coefficient is around α ∼ 1.0 [cm −1 ] [30]. Depending on the thickness, the Fabry-Perot interference in the SiN membrane significantly modulates transmission, which can be used to increase detection selectivity at specific wavelengths or to render the membrane transparent even at a high irradiance [31].…”

Fabry-Pérot sensors: microfluidic channels and transparent membranes

“…By controlling the thicknesses of silicon and oxide layers it is possible to realize highly transparent membrane for a particular wavelength used for laser trapping or an auxiliary irradiation as as we demonstrated earlier. 25 Small mechanically or thermally induced changes of membrane thickness can be used for sensing as discussed next.…”

Edge-induced flattening in the fabrication of ultrathin freestanding crystalline silicon sheets

“…Fabrication of such membranes has been successful in metallic systems, 6,7 but has proven challenging in semiconductors like silicon. Freestanding silicon membranes have applications in electronic and photonic materials, [8][9][10][11] micromechanical devices, [12][13][14][15][16] x-ray optics, [17][18][19] macromolecular filters, 20 lithographic templates, 17,19 as sensors, 21,22 and as low-absorption supports in transmission electron microscopy. All of these applications benefit from flat crystalline structures with low lateral inhomogeneity.…”

“…The process begins with a silicon-on-insulator (SOI) substrate and uses an anisotropic wet etching procedure starting from a photolithographic pattern on the back of the handle wafer, similar to previous reports. 16,17,21,22,25 Edge-supported membranes are released by removing the buried oxide (BOX) layer from beneath a region of the device layer. Si membranes with a large range of thicknesses from tens of lm 18,25 to tens of nm have been fabricated using this approach.…”

“…Si membranes with a large range of thicknesses from tens of lm 18,25 to tens of nm have been fabricated using this approach. 14,16,17,[19][20][21][22]24,26,27 Buckling often occurs in these structures as a result of compressive stresses in the silicon device layer. Previous attempts to create flat semiconductor membranes have used either strain relief structures 5,14,15 or the deposition of a tensile-stressor overlayer.…”