High-density regular arrays of nanometer-scale rods formed on silicon surfaces via femtosecond laser irradiation in water.

We report on the formation of high-density regular arrays of nanometer-scale rods using femtosecond laser irradiation of a silicon surface immersed in water. The resulting surface exhibits both micrometer-scale and nanometer-scale structures. The micrometer-scale structure consists of spikes of 5-10 mum width, which are entirely covered by nanometer-scale rods that are roughly 50 nm wide and normal to the surface of the micrometer-scale spikes.

Enhancing near-infrared avalanche photodiode performance by femtosecond laser microstructuring.

A processing technique using femtosecond laser pulses to microstructure the surface of a silicon avalanche photodiode (APD) has been used to enhance its near-infrared (near-IR) response. Experiments were performed on a series of APDs and APD arrays using various structuring parameters and poststructuring annealing sequences. Following thermal annealing, we were able to fabricate APD arrays with quantum efficiencies as high as 58% at 1064 nm without degradation of their noise or gain performance.

Superhydrophobic surfaces prepared by microstructuring of silicon using a femtosecond laser.

We present a simple method for fabricating superhydrophobic silicon surfaces. The method consists of irradiating silicon wafers with femtosecond laser pulses and then coating the surfaces with a layer of fluoroalkylsilane molecules. The laser irradiation creates a surface morphology that exhibits structure on the micro- and nanoscale.

Visible and near-infrared responsivity of femtosecond-laser microstructured silicon photodiodes.

We investigated the current-voltage characteristics and responsivity of photodiodes fabricated with silicon that was microstructured by use of femtosecond-laser pulses in a sulfur-containing atmosphere. The photodiodes that we fabricated have a broad spectral response ranging from the visible to the near infrared (400-1600 nm). The responsivity depends on substrate doping, microstructuring fluence, and annealing temperature.