A new approach to white light emitting diodes of p-GaN/i-ZnO/n-ZnO heterojunctions

Micro- and mesoporous supports for CO2 methanation catalysts: A comparison between SBA-15, MCM-41 and USY zeolite

“…SBA-15 catalysts preserved the three peaks attributed to the diffraction of the (100), (110) and (200) characteristic planes of the highly ordered hexagonal structure of SBA-15 at ~ 0.9, 1.5 and 1.7º 23 . On the contrary, the peaks attributed to the MCM-41 structure (~ 2.1, 4.0 and 4.6º 24 ) were not clearly observed for the Ni and Ni-Ce/MCM-41 catalysts, which could be due to a migration of a greater fraction of metallic species to the pores during the catalytic test and/or a partial loss of the ordered hexagonal pore structure arrangement of the material 13,25 . Regarding the wide angle patterns, all samples presented an important decrease on the peaks intensity as already seen in the literature 26 , being only observed in some cases the characteristic peaks of Ni 0 .…”

“…The peaks attributed to the MCM-41 structure were also detected for the as-synthesized support at ~ 2.1, 4.0 and 4.6 corresponded to the (100), (110), and (200) diffraction planes of this material 24 . Introduction of Ni and Ce leads in all the cases to a decrease of the peaks intensities, which could be due the presence of the metal oxides and/or a partial damage of the ordered hexagonal pore structure specially for the MCM-41 samples in the (100) diffraction peak 13,25 . Concerning the wide angle XRD patterns ( Figure 1B and Figure 2B), the presence of amorphous SiO2 (broad diffraction peak around 22.3º) and NiO ), whereas for the 15%Ni/HNaUSY(2.8) zeolite UV bands for both NiO and Ni 2+ were observed 6 .…”

Growth habit control of ZnO single crystals in molten hydrous alkali solutions

“…Zinc oxide dissolves in an alkali to form [Zn(OH) 2 [16]. According to the anion coordination polyhedron model, the coordination structure of the growth unit should be consistent with the crystal symmetry.…”

“…It has attracted a great deal of attention for optoelectronic applications in ultraviolet lasers [1] and light-emitting diodes [2] due to its wide band gap (3.37 eV) and large exciton-binding energy (60 meV), as well as its possible use as an alternative substrate for GaN epilayers with a lattice mismatch of less than 1.8% [3].…”

Defect-Related White-Light Emission from ZnO in an n-Mg0.2Zn0.8O/n-ZnO/SiO x Heterostructure on n-Si

“…However, reports on white-light electroluminescence (EL) of ZnO films are rare. 3,4 As is well known, undoped ZnO usually exhibits n-type conductivity, which has been attributed to the presence of unintentional hydrogen doping or native defects such as zinc interstitials and oxygen vacancies. 5,6 The realization of ZnO LEDs suffers from the difficulty of reproducible p-type doping of ZnO with high concentration.…”