We report the effects of the growth ambient on photoluminescence (PL) emission properties of ZnO films grown on Si (100) by rf magnetron sputtering. Upon increasing the O2/Ar+O2 ratio in the growing ambient, the visible emission in the room-temperature PL spectra was drastically suppressed without sacrificing the band-edge emission intensity in the ultraviolet region. This tendency is estimated to be due to the reduction of the oxygen vacancies and zinc interstitials in the film induced by the improvement of the film stoichiometry with respect to high oxygen content, indicating that the visible emission in ZnO originates from oxygen vacancy or zinc interstitial related defects. The violet emission peaked at about 401 nm (3.09 eV) was observed in the low-temperature PL spectra of the ZnO films grown under oxygen-rich conditions. This emission band was assigned to the electron transition from the bottom of the conduction band to the Zn vacancy level, positioned approximately 3.06 eV below the conduction band edge.

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In this article it is shown that high quality single crystalline Ga-doped ZnO (GZO) films could be achieved on ac-plane sapphire using conventional rf magnetron sputtering. High-resolution x-ray diffractometry, transmission electron microscopy (TEM), and scanning electron microscopy investigations clearly confirmed that the GZO films with low Ga doping levels up to 1wt% were of high quality single crystal, which is featured by the (0002) rocking curve as narrow as 0.14°, symmetric six poles in pole figure, sharply defined spot pattern in the TEM diffraction diagram of the interfacial region, and the flat surface. It was also estimated from the Hall measurements and photoluminescence spectroscopy that these single crystalline GZO films possessed good optical and electrical characteristics including the narrow band-width and higher intensity of exciton-related emission peak, Hall mobility as large as 66 cm2 V−1 s−1, and the resistivity as low as 1.69 × 10− 3 Ω cm.

Developing a highly efficient and ecofriendly system to produce desired products from waste can be considered important to a sustainable society. Here, we report for the first time high-yield production of lycopene through metabolically engineering an extremophilic microorganism, Deinococcus radiodurans R1, from corn steep liquor (CSL) and glycerol. First, the crtLm gene-encoding lycopene cyclase was deleted to prevent the conversion of lycopene to γ-carotene. Then, the crtB gene-encoding phytoene synthase and the dxs gene-encoding 1-deoxy-d-xylulose 5-phosphate synthase were overexpressed to increase carbon flux toward lycopene. The engineered ΔcrtLm/crtB + dxs + D. radiodurans R1 could produce 273.8 mg/L [80.7 mg/g dry cell weight (DCW)] and 373.5 mg/L (108.0 mg/g DCW) of lycopene from 10 g/L of glucose with 5 g/L of yeast extract and 9.9 g/L of glucose with 20 g/L of CSL, respectively. Moreover, the lycopene titer and content were increased by 26% (470.6 mg/L) and 28% (138.2 mg/g DCW), respectively, when the carbon source was changed to glycerol. Finally, fed-batch fermentation of the final engineered strain allowed the production of 722.2 mg/L (203.5 mg/g DCW) of lycopene with a yield and productivity of 20.3 mg/g glycerol and 6.0 mg/L/h, respectively, from 25 g/L of CSL and 35.7 g/L of glycerol.