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Go to Editorial ManagerSurface reconstruction of silicon using lasers could be utilized to produce silicon nanostructures of various features. Electrochemical and photoelectrochemical etching processes of silicon were employed to synthesize nanostructured surface. Effects of current densities 5, 10 and 20 mA/cm2 on the surface features were examined. It is found that the surface porosity and layer thickness increase with the current density. Moreover, large surface area of 410 m2/cm3 can be achieved when laser power density 0f 0.6 W/cm2 was used during the etching process. Optimum operating conditions were found to achieve better silicon nanostructured surface features. The surface roughness can be reduced to 8.3 nm using laser beam of 650 nm irradiated the silicon surface during the photoelectrochemical etching process. The surface morphology of the nanostructured silicon surface using SEM and AFM could give rich details about the surface. Silver nanoparticles of 10 – 20 nm was embedded at the nanostructured silicon surface by LIFT process to reduce the surface resistance and maintain the large surface area. This technique enables silicon nanostructures to be efficiently used in many optoelectronic applications.
Two lasers were utilized for silicon processing using photoelectrochemical etching and laser texturing in order to produce nano/micro structures, respectively. Photoelectrochemical etching process utilizes a CW diode laser of 532 nm wavelength was used to support electrochemical etching for both n-type and p-type conductivity. While laser texturing process was employed using pulsed fiber laser of 1064 nm wavelength. Various characterization methods were devoted to examine silicon micro/nanostructures surfaces produced by lasers. These methods include AFM, SEM and Raman scattering to provide clear evidence about formation of micro/nanostructures abundant at silicon surfaces. Moreover, FTIR analysis for the laser produced silicon surfaces could emphasize whether the resultant silicon surface is hydrophilic or hydrophobic. Image analysis software adopted a side view micro image was used to measure the contact angle between the water droplet and silicon micro/nano-surfaces. It is found that the laser produced silicon nanostructure by photoelectrochemical etching creates a hydrophobic surface and even super hydrophobic with contact angle of 130 degrees for 50 nm average size. In addition, utilizing fiber laser of high repetition rate for laser texturing produces microstructures that are super hydrophilic with contact angle could reach 8 degrees for a surface dimension of 50 μm.