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Spontaneous formation of nanospiked microstructures in germanium by femtosecond laser irradiation

Nayak, Barada K. and Gupta, Mool C. and Kolasinski, Kurt W. (2007) Spontaneous formation of nanospiked microstructures in germanium by femtosecond laser irradiation. NANOTECHNOLOGY, 18 (19).

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Official URL: http://www.iop.org/EJ/abstract/0957-4484/18/19/195...

Abstract

We report a novel phenomenon of spontaneous formation of nearly regular arrays of nanospikes atop conical microstructures by exposing a germanium surface to femtosecond laser pulses in an environment of SF6. Silicon laser texturing has been reported, but no information has been published on laser microtexturing of Ge and in particular the observation of nanospikes atop conical microstructures. The nanospikes are around 2 µm high having a tip radius of 100 nm and are formed atop conical microstructures that are around 5 µm wide and 10 µm tall. The tip radius could be sharpened down to ~10 nm by brief chemical etching. A higher laser fluence and fewer shots favour the formation of nanospikes. By increasing the number of shots at higher fluence the surface morphology changes from conical microstructures to tall straight-walled pillar-like structures and the nanospikes disappear. The surface morphology of germanium has been compared with silicon. The germanium samples turn completely black after laser processing, i.e. they exhibit greatly reduced reflectivity throughout the visible spectrum.

Item Type:Article
Subjects:Material Science > Nanostructured materials
ID Code:6255
Deposited By:IoN
Deposited On:14 Jan 2010 15:55
Last Modified:14 Jan 2010 15:55

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