@article {Younkin:148, title = {Infrared absorption by conical silicon microstructures made in a variety of background gases using femtosecond-laser pulses}, journal = {J. Appl. Phys.}, volume = {93}, year = {2003}, pages = {2626{\textendash}2629}, abstract = {We show that the near-unity infrared absorptance of conical microstructures fabricated by irradiating a Si(111) surface with 100-fs laser pulses depends on the ambient gas in which the structures are formed. Of the background gases we investigate, SF6 is the most effective, yielding an absorptance of 0.9 for radiation in the 1.2-2.5 m wavelength range. Use of Cl2, N2, or air produces surfaces with absorptances intermediate between that for microstructures formed in SF6 and that for flat, crystalline silicon, for which the absorptance is roughly 0.05?0.2 for a 260- m thick sample.}, doi = {10.1063/1.1545159}, url = {/files/mazur/files/rep_148.pdf}, author = {R. J. Younkin and J. E. Carey and Mazur, E. and J. A. Levinson and Friend, C. M.} }