Electroplating Cobalt Films on Silicon Nanostructures for Sensing Molecules.

In this study, we electroplated Co and Cu on nano-spiked silicon substrates that were treated with femtosecond laser irradiations. With energy-dispersive X-ray (EDX) analysis by a scanning electron microscope (SEM), it was found that both Co and Cu are primarily coated on the spike surfaces without changing the morphology of the nanospikes. We also found that nanoscale bridges were formed, connecting the Co-coated silicon spikes.

Surface-assisted laser desorption and ionization mass spectrometry using low-cost matrix-free substrates.

Surface-assisted laser desorption/ionization (SALDI) substrates have been fabricated using nanospiked polyurethane (PU) substrates that are replicated by a low-cost soft nanolithography method from silicon nanospike structures formed with femtosecond laser irradiations. The strongest mass spectrometry (MS) signal of Angiotensin II was obtained on 45-nm Au-coated nanospiked PU substrates. The effective ionization appears to be due to surface plasmon excitation.

The thresholds of surface nano-/micro-morphology modifications with femtosecond laser pulse irradiations.

We studied the pulse energy threshold of surface nano-/micro-morphology modifications by irradiating Si, GaAs, GaP, InP, Cu and Ti surfaces with 100 fs laser pulses at a wavelength of 800 nm in air and in water. We found that the laser pulse energy thresholds required for the permanent modification in water are up to 30% lower than those in air. Different non-equilibrium dynamics processes of the surface melting layer cause the different thresholds in water and in air.

Surface-enhanced Raman scattering sensor on an optical fiber probe fabricated with a femtosecond laser.

A novel fabrication method for surface-enhanced Raman scattering (SERS) sensors that used a fast femtosecond (fs) laser scanning process to etch uniform patterns and structures on the endface of a fused silica optical fiber, which is then coated with a thin layer of silver through thermal evaporation is presented. A high quality SERS signal was detected on the patterned surface using a Rhodamine 6G (Rh6G) solution. The uniform SERS sensor built on the tip of the optical fiber tip was small, light weight, and could be especially useful in remote sensing applications.

High-performance logic circuits constructed on single CdS nanowires.

A high-performance NOT logic gate (inverter) was constructed by combining two identical n-channel metal-semiconductor field-effect transistors (MESFETs) made on a single CdS nanowire (NW). The inverter has a voltage gain as high as 83, which is the highest reported so far for inverters made on one-dimensional nanomaterials. The MESFETs used in the inverter circuit show excellent transistor performance, such as high on/off current ratio ( approximately 10(7)), low threshold voltage ( approximately -0.