[en] A series of solid electrolytes Ce_1-xSm_xO_2-y (x=0∼0.6) were prepared by sol-gel method. XRD measurement showed that single-phase solid solution was formed in all investigated ranges at 160 deg. C, which is a significantly lower synthesis temperature compared to traditional solid state reaction. High temperature X-ray, ESR, and Raman scattering were used to characterize the samples. ESR measurement showed that ESR with sample irradiated by high-energy particle is an effective way to study the defect structure. These changes in the Raman spectrum are attributed to O vacancies, which are introduced into the lattice when tetravalent Ce⁴⁺ is substituted by trivalent Sm³⁺

[en] ZnO nanowires with different arsenic concentration were grown on Si (1 0 0) substrates by chemical vapor deposition method without using catalyst. Zn/GaAs mixed powders were used as Zn and As source, respectively. Oxygen was used as oxidant. The images of scanning electron microscope show that the arsenic-doped ZnO nanowires with preferred c-axial orientation were obtained, which is in well accordance with the X-ray diffraction analysis. The arsenic related acceptor emission was observed in the photoluminescence spectra at 11 K for all arsenic-doped ZnO samples. This method for the preparation of arsenic-doped ZnO nanowires may open the way to realize the ZnO nanowires based light-emitting diode and laser diode.

[en] In this paper, highly oriented and vertically arranged ZnO nanotubes are prepared on Al₂O₃ (0001) substrate without employing any metal catalysts by plasma-assisted molecular beam epitaxy. The photoluminescence (PL) spectra at room temperature are studied under high excitation densities. Under lower excitation density (<60kW/cm²), PL spectrum shows that one strong free exciton emission (FE) locates at 3.306eV. As the excitation density increases up to 200kW/cm², a new emission peak (P_n) located at low-energy side of FE is attributed to the spontaneous emission due to an exciton-exciton (E_x-E_x) scattering process from two ground state excitons, where one exciton is recombined by emitting a photon and the other is scattered into the excited states of n=2,3,4...∼. Under excitation density of 300kW/cm², the stimulated emission originating from E_x-E_x scattering is obtained. When the excitation density is above 580kW/cm², the emission from electron-hole plasma is observed in low-energy side of the P band and indicates a typical superradiation recombination processes with increasing excitation density

[en] The heterojunction light-emitting diode with n-ZnO/p-GaN structure was grown on (0 0 0 1) sapphire substrate by metalorganic chemical vapor deposition (MOCVD) technique. The heterojunction structure was consisted of an Mg-doped p-type GaN layer with a hole concentration of ∼10¹⁷ cm^-3 and a unintentionally doped n-type ZnO layer with an electron concentration of ∼10¹⁸ cm^-3. A distinct blue-violet electroluminescence with a dominant emission peak centered at ∼415 nm was observed at room temperature from the heterojunction structure under forward bias conditions. The origins of the electroluminescence (EL) emissions are discussed in comparison with the photoluminescence spectra, and it was supposed to be attributed to a radiative recombination in both n-ZnO and p-GaN sides