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- Derenzo, S. E., et al.
(author)
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Scintillation studies of CdS(In): effects of various semiconductor doping strategies
- 2005
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002. ; 537:1-2, s. 261-
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Journal article (peer-reviewed)abstract
- We present room-temperature photoluminescence and pulsed X-ray measurements of powder samples of CdS(In) codoped with three hole traps (Te, Ag, and Na). Te is an isoelectronic hole trap and Ag, and Na are acceptor hole traps. The emission of CdS(In) excited at 430 nm is centered at approximate to 520 nm (near the band edge) with approximate to 20 nm FWHM. The emissions from CdS(Te) and the three codoped samples are shifted to longer wavelengths and are characterized by broad emission bands peaking near 630 nm. Whereas the decay of the CdS(Te) emission is nonexponential with times > 10 its, the decay of CdS(In, Te) is 3.3 ns and exponential over three decades. The decay of the acceptor-doped samples CdS(In,Ag) and CdS(In, Na) are also fast, 2.5 and 2.8 ns, respectively. These results show the potential for developing fast inorganic scintillators based on direct-gap semiconductors that can be codoped to provide fast radiative recombination. Additional work is needed to increase the luminosity.
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- Lebegue, S, et al.
(author)
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Accurate electronic band gap of pure and functionalized graphane from GW calculations
- 2009
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 79:24, s. 245117-
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Journal article (peer-reviewed)abstract
- Using the GW approximation, we study the electronic structure of the recently synthesized hydrogenated graphene, named graphane. For both conformations, the minimum band gap is found to be direct at the Gamma point, and it has a value of 5.4 eV in the stable chair conformation, where H atoms attach C atoms alternatively on opposite sides of the two-dimensional carbon network. In the metastable boat conformation the energy gap is 4.9 eV. Then, using a supercell approach, the electronic structure of graphane was modified by introducing either a hydroxyl group or an H vacancy. In this last case, an impurity state appears at about 2 eV above the valence-band maximum.
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