Tuesday, October 16, 2001
Physics and Advanced Technologies Seminar, Lawrence Livermore National Laboratory (Livermore, CA)
Arrays of sharp, conical microstructures are obtained by texturing the surface of a silicon wafer using femtosecond laser-assisted chemical etching. The one step, maskless texturing process drastically changes the optical, material and electronic properties of the original silicon wafer. These properties make the textured silicon viable for use in a wide range of commercial devices. First, near-unity absorption of light, from visible to infrared wavelengths, offer opportunities for use in optically active devices such as solar cells and detectors. Significant enhancement of below-band-gap photocurrent generation in textured avalanche photodiodes shows strong promise for use in infrared photodetectors. Second, chemical functionalization of the increased surface area indicate great potential of the textured silicon for novel chemical and biological sensing applications. Third, remarkable field emission characteristics have direct applications in the rapidly growing industry of field emission devices. The low turn-on fields and high current yields make the textured silicon ideal for use in field emission displays, ion thruster propulsion, and microwave amplification. The use of silicon is particularly interesting in commercial application due to the low cost and prevalence of silicon in electronics.