Publications

    J. E. Carey and E. Mazur. 2003. “Femtosecond Laser-Assisted Microstructuring of Silicon for Novel Detector, Sensing and Display Technologies.” In . LEOS 2003. Publisher's VersionAbstract
    Arrays of sharp, conical microstructures are obtained by stucturing the surface of a silicon wafer using femtosecond laser-assisted chemical etching. The one step, maskless structuring process drastically changes the optical, material and electronic properties of the original silicon wafer. These properties make microstructured silicon viable for use in a wide range of commercial devices including solar cells, infrared photodetectors, chemical and biological sensors, and field emission devices.
    M. Shen, C. H. Crouch, J. E. Carey, R. J. Younkin, E. Mazur, M. A. Sheehy, and C. M. Friend. 2003. “Formation of regular arrays of silicon microspikes by femtosecond laser irradiation through a mask.” Appl. Phys. Lett., 82, Pp. 1715–1717. Publisher's VersionAbstract
    We report fabrication of regular arrays of silicon microspikes by femtosecond laser irradiation of a silicon wafer covered with a periodic mask. Without a mask, microspikes form, but they are less ordered. We believe that the mask imposes order by diffracting the laser beam and providing boundary conditions for capillary waves in the laser-melted silicon.
    R. J. Younkin, J. E. Carey, E. Mazur, J. A. Levinson, and C. M. Friend. 2003. “Infrared absorption by conical silicon microstructures made in a variety of background gases using femtosecond-laser pulses.” J. Appl. Phys., 93, Pp. 2626–2629. Publisher's VersionAbstract
    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.
    C. Wu, C. H. Crouch, L. Zhao, J. E. Carey, R. J. Younkin, J. A. Levinson, E. Mazur, R. M. Farrel, P. Gothoskar, and A. Karger. 2001. “Near-unity below-band gap absorption by microstructured silicon.” Appl. Phys. Lett., 78, Pp. 1850–1852. Publisher's VersionAbstract
    We increased the absorptance of light by silicon to approximately 90% from the near ultraviolet (0.25 m) to the near infrared (2.5 m) by surface microstructuring using laser-chemical etching. The remarkable absorptance most likely comes from a high density of impurities and structural defects in the silicon lattice, enhanced by surface texturing. Microstructured avalanche photodiodes show significant enhancement of below-band gap photocurrent generation at 1.06 and 1.31 m, indicating promise for use in infrared photodetectors.

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