Arturo Hidalgo

Ultraviolet photosensitivity of sulfur-doped micro- and nano-crystalline diamond

The room-temperature photosensitivity of sulfur-doped micro-, submicro-, and nano-crystalline diamond films synthesized by hot-filament chemical vapor deposition was studied. The structure and composition of these diamond materials were characterized by Raman spectroscopy, scanning electron microscopy, and x-ray diffraction. The ultraviolet (UV) sensitivity and response time were studied for the three types of diamond materials using a steady-state broad UV excitation source and two pulsed UV laser radiations. It was found that they have high sensitivity in the UV region (as high as 109 s−1 mV−1 range), a linear response in a broad spectral range below 320 nm, photocurrents around ∼10−5 A, and a short response time better than 100 ns, which is independent of fluency intensity. A phenomenological model was applied to help understand the role of defects and dopant concentration on the materials’ photosensitivity.The room-temperature photosensitivity of sulfur-doped micro-, submicro-, and nano-crystalline diamond films synthesized by hot-filament chemical vapor deposition was studied. The structure and composition of these diamond materials were characterized by Raman spectroscopy, scanning electron microscopy, and x-ray diffraction. The ultraviolet (UV) sensitivity and response time were studied for the three types of diamond materials using a steady-state broad UV excitation source and two pulsed UV laser radiations. It was found that they have high sensitivity in the UV region (as high as 109 s−1 mV−1 range), a linear response in a broad spectral range below 320 nm, photocurrents around ∼10−5 A, and a short response time better than 100 ns, which is independent of fluency intensity. A phenomenological model was applied to help understand the role of defects and dopant concentration on the materials’ photosensitivity.

TOF MS studies concerning the synthesis of B-N and B-C-N nanaostructured materials by laser ablation

Time-of-flight mass spectroscopy (TOF MS) spectra of ions ablated from BN-ceramic, amorphous carbon, graphite and fullerene-60 targets were recorded at different experimental conditions. It was found that the TOF MS spectra significantly simplify as the energy density of the laser radiation was increased, and show temporal evolution as the distance between the target surface and work area of TOF MS is increased. Moreover, the spectral line widths significantly increase with increasing laser radiation density and distance between target surface and work area of TOF MS. Analyses of these data allowed to estimate the average velocity of the ablated beam center of mass as well as the average energy of ions in the ablated plasma. Assignment of the spectral lines was also done. The data obtained can be used to optimize the synthesis nanostructured B-N and B-C-N materials by laser ablation.