Abstract: A system and method for determining a doping profile of a sample includes a generator and at least one detector of terahertz light of multiple frequencies, configured to operate in a transmission and/or reflection mode; a materials refractive index library; and an inverse algorithm that can match simulated spectra using a trial doping profile and the materials library with the measured spectra from a sample, and map out or measure an activated doping profile into, or a free carrier distribution into, the interior of the sample.

Abstract: A system and method for determining a doping profile of a sample includes a generator and at least one detector of terahertz light of multiple frequencies, configured to operate in a transmission and/or reflection mode; a materials refractive index library; and an inverse algorithm that can match simulated spectra using a trial doping profile and the materials library with the measured spectra from a sample, and map out or measure an activated doping profile into, or a free carrier distribution into, the interior of the sample.

Abstract: A solar cell includes a plurality of nanostructures. The nanostructures include a first metal oxide, each of the plurality of the nanostructures having a surface defining a cavity opening into an upper side. The solar cell further includes a layer of a second metal oxide disposed over the surface in at least some of the plurality of the nanostructures and a filler material disposed over the layer and filling at least partially the cavity of at least some of the plurality of the nano structures.

Abstract: A method of preparing titania nanotubes involves anodization of titanium in the presence of chloride ions and at low pH (1-7) in the absence of fluoride. The method leads to rapid production of titania nanotubes of about 25 nm diameter and high aspect ratio. The nanotubes can be organized into bundles and tightly packed parallel arrays. Inclusion of organic acids in the electrolyte solution leads to the incorporation into the nanotubes of up to 50 atom percent of carbon. In a two-stage method, a titanium anode is pre-patterned using a fluoride ion containing electrolyte and subsequently anodized in a chloride ion containing electrolyte to provide more evenly distributed nanotube arrays. The titania nanotubes have uses in composite materials, solar cells, hydrogen production, and as hydrogen sensors.

Abstract: A method of preparing titania nanotubes involves anodization of titanium in the presence of chloride ions and at low pH (1-7) in the absence of fluoride. The method leads to rapid production of titania nanotubes of about 25 nm diameter and high aspect ratio. The nanotubes can be organized into bundles and tightly packed parallel arrays. Inclusion of organic acids in the electrolyte solution leads to the incorporation into the nanotubes of up to 50 atom percent of carbon. In a two-stage method, a titanium anode is pre-patterned using a fluoride ion containing electrolyte and subsequently anodized in a chloride ion containing electrolyte to provide more evenly distributed nanotube arrays. The titania nanotubes have uses in composite materials, solar cells, hydrogen production, and as hydrogen sensors.