Presentations

    Femtosecond laser doping of TiO2 for solar harvesting, at Photonics West (San Fransisco, CA), Tuesday, January 24, 2012:
    We present a novel method for femtosecond-laser doping of titanium dioxide (TiO2) for above bandgap absorptance by irradiating titanium metal in the presence of oxygen and dopants. With a bandgap of 3.2 eV for the anatase crystalline phase, TiO2 most strongly absorbs in the UV range (λ < 387 nm). However, doping with metals and nitrogen has been shown to create intermediate states in the bandgap. Using femtosecond laser doping techniques on titanium in a gaseous environment, we produce laser-induced periodic surface structures. Altering the gas composition and pressure does not change the... Read more about Femtosecond laser doping of TiO2 for solar harvesting
    Femtosecond laser doped and nanostructured TiO2 for photocatalysis, at American Physical Society March Meeting (Boston, MA), Monday, February 27, 2012:
    We present a novel method for femtosecond-laser doping of titanium dioxide (TiO2) for above bandgap absorptance by irradiating titanium metal in the presence of oxygen and dopants. With a bandgap of 3.2 eV for the anatase crystalline phase, TiO2 most strongly absorbs in the UV range (λ< 387 nm). However, doping with metals and nitrogen has been shown to create intermediate states in the bandgap. Using femtosecond laser doping techniques on titanium in a gaseous environment, we produce laser-induced periodic surface structures. Altering the gas composition and pressure does not change the... Read more about Femtosecond laser doped and nanostructured TiO2 for photocatalysis
    Femtosecond laser doping of TiO2 for photocatalysis, at Gordon Research Seminar on Renewable Energy: Solar Fuels (Barga, Italy), Saturday, May 12, 2012:
    We present a novel method for femtosecond-laser doping of titanium dioxide (TiO2) for above bandgap absorptance by irradiating titanium metal in the presence of oxygen and dopants. With a bandgap of 3.2 eV for the anatase crystalline phase, TiO2 most strongly absorbs in the UV range (λ < 387 nm). However, doping with metals and nitrogen has been shown to create intermediate states in the bandgap. Using femtosecond laser doping techniques on titanium in a gaseous environment, we produce laser-induced periodic surface structures. Altering the gas composition and pressure does not change the... Read more about Femtosecond laser doping of TiO2 for photocatalysis
    Femtosecond laser texturing and doping of metals and semiconductors for solar harvesting, at SPIE Optics and Photonics (San Diego, CA), Thursday, August 16, 2012:
    Shining intense, ultrashort laser pulses on the surface of a crystalline silicon wafer drastically changes the optical, material and electronic properties of the wafer. The resulting textured surface is highly absorbing and looks black to the eye. The properties of this 'black silicon' make it useful for a wide range of commercial devices. In particular, we have been able to fabricate highly-sensitive PIN photodetectors using this material. The sensitivity extends to wavelengths of 1600 nm making them particularly useful for applications in communications and remote sensing.
    Formation of mixed metal oxides by femtosecond laser irradiation for solar harvesting, at SPIE Photonics West (San Francisco, CA), Tuesday, February 5, 2013
    We present a novel method for producing mixed metal oxides using femtosecond laser doping of metallic foil in the presence of oxygen and another metallic dopant. We discuss doping titanium dioxide (TiO2) for above bandgap absorptance by irradiating titanium metal with an evaporated thin film of metal. As a wide bandgap, TiO2 most strongly absorbs in the UV range (?... Read more about Formation of mixed metal oxides by femtosecond laser irradiation for solar harvesting
    Femtosecond laser doping of TiO2 for photocatalysis, at Photonics West (San Fransisco, CA), Monday, January 24, 2011:
    We present a novel method for femtosecond-laser doping of titanium dioxide (TiO2) for enhanced absorptance in the visible electromagnetic spectrum. With a bandgap of 3.2 eV for the anatase crystalline phase, TiO2 most strongly absorbs in the UV range ( < 387 nm). However, doping with metals and nitrogen has been shown to create intermediate states in the bandgap, generating a new material for visible-light photocatalysis that has the potential for watersplitting. Using femtosecond laser doping techniques on bulk TiO2 in a gaseous environment, we produce laser-induced periodic surface... Read more about Femtosecond laser doping of TiO2 for photocatalysis
    Femtosecond laser production of TiO2, at Hyperdoping Research Meetup, MIT (Cambridge, MA), Friday, April 15, 2011:
    We present a novel method for producing TiO2 through femtosecond-laser processing titanium in the presence of oxygen. The process produces laser-induced periodic surface structures that are consistent with previous work done on titanium. We compare how the surface morphology and composition vary with gas composition and laser parameters. Using x-ray photoelectron and Raman spectroscopy, we will show that chemical selectivity plays an important role in hyperdoping titanium. With this method, we hope to introduce dopants, such as chromium and nitrogen, into the lattice for visible light... Read more about Femtosecond laser production of TiO2
    Black silicon and the quest for intermediate band semiconductors, at Laser-Based Micro and Nano Processing VIII, Photonics West 2014 (San Francisco, CA), Thursday, February 6, 2014:
    Shining intense, ultrashort laser pulses on the surface of a crystalline silicon wafer drastically changes the optical, material and electronic properties of the wafer. The process has two effects: it structures the surface and incorporate dopants into the sample to a concentration highly exceeding the equilibrium solubility limit. This femtosecond laser "hyperdoping technique" enables the fabrication of defect- and bandgap engineered semiconductors, and laser texturing further enhances the optical density through excellent light trapping. Hyperdoped silicon opens the door for novel... Read more about Black silicon and the quest for intermediate band semiconductors