Reproducible Sb-doped p-type ZnO films were grown on n-Si (100) by electron-cyclotron-resonance-assisted molecular-beam epitaxy. The existence of Sb in ZnO:Sb films was confirmed by low-temperature photoluminescence measurements. An acceptor-bound exciton (A°X) emission was observed at 3.358 eV at 8 K. The acceptor energy level of the Sb dopant is estimated to be 0.2 eV above the valence band. Temperature-dependent Hall measurements were performed on Sb-doped ZnO films. At room temperature, one Sb-doped ZnO sample exhibited a low resistivity of 0.2Ωcm, high hole concentration of 1.7×1018cm−3 and high mobility of 20.0cm2∕Vs. This study suggests that Sb is an excellent dopant for reliable and reproducible p-type ZnO fabrication.
We investigated photoluminescence ͑PL͒ from reliable and reproducible Sb-doped p-type ZnO films grown on n-Si ͑100͒ by molecular-beam epitaxy. Well-resolved PL spectra were obtained from completely dopant-activated samples with hole concentrations above 1.0ϫ 10 18 cm −3. From free electron to acceptor transitions, acceptor binding energy of 0.14 eV is determined, which is in good agreement with analytical results of the temperature-dependent PL measurements. Another broad peak at 3.050 eV, which shifts to lower energy at higher temperatures, indicates the formation of deep acceptor level bands related to Zn vacancies, which are created by Sb doping.
A facile pulse laser ablation approach for preparing black titanium oxide nanospheres, which could be used as photocatalysts under visible light, is proposed. The black titanium oxide nanospheres are prepared by pulsed-laser irradiation of pure titanium oxide in suspended aqueous solution. The crystalline phases, morphology, and optical properties of the obtained nanospheres are characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and UV-vis-NIR diffuse reflectance spectroscopy. It is shown that high-energy laser ablation of titanium oxide suspended solution benefited the formation of Ti(3+) species and surface disorder on the surface of the titanium oxide nanospheres. The laser-modified black titanium oxide nanospheres could absorb the full spectrum of visible light, thus exhibiting good photocatalytic performance under visible light.
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