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Highlights: [•] We have demonstrated the chemical reaction, charge and energy transfer process using photoelectron spectroscopy for near-infrared organic light-emitting diodes. [•] Based on the result of this paper, we can achieve the optimal device efficiency by certain of ErF3 dopant concentration, which is useful for the research of NIR-OLED. [•] The study on the electroluminescence mechanism is crucial for the applying of ErF3 doped NIR-OLED. [Copyright &y& Elsevier]

We have demonstrated that the thickness of the catalyst layer plays a significant role in the morphology and the material quality of the InN nanocolumns grown on Si(111) substrate by plasma-assisted molecular beam expitaxy using vapor-liquid-solid method. A systematic investigation of In catalyst films was undertaken, revealing that high density uniform InN can not be obtained when the In catalyst is either too thin or too thick and the appropriate thickness of the deposited In was 1 nm. The influence of V/III radio on the growth procedure is also discussed, and as proved, a higher V/III radio is necessary to be used to get high density nanocolumns and improved optical property. [ABSTRACT FROM AUTHOR]

A highly sensitive H 2 gas sensor based on n-WO 3 /p-PdO heterostructure has been fabricated. Using hydrothermal method, through tuning the pH value of the solution, WO 3 nanospindles were synthesized. SEM reveals its uniform morphology; XRD result shows its high crystal quality; N 2 adsorption/desorption result proves its relatively high specific surface area. Through first soaking then calcinating method, PdO was loaded on the surface of WO 3 nanospindles. XPS and HRTEM together have proved the fabrication of the heterostructure between n-WO 3 /p-PdO. The gas sensing device was fabricated by coating the PdO loaded WO 3 paste on a ceramic substrate with silver palladium interdigital electrodes. After loaded into the test chamber, preheated to the required temperature and injecting a certain amount of H 2 , the sensing procedure was done. With optimal ratio of loaded PdO to WO 3 (3 at%), the sensor shows the best gas sensitivity at 150 °C. To 1, 5, 10, 20 and 50 ppm H 2 , the sensor shows the response values (R a /R g) of 1.3, 7, 23, 37 and 76, in the response time of 9s, 8s, 5s, 3s and 1s, respectively. The quasi-one dimensional (QOD) character of WO 3 nanospindle, the well-performance heterostructure between WO 3 and PdO and the optimal ratio of loaded PdO to WO 3 together make the sensor own strong sensing ability towards H 2. The such well-performance H 2 gas sensor based on n-WO 3 /p-PdO heterostructure reminds us that the WO 3 /PdO system has supplied a good material platform to explore the fabrication of ultrasensitive and stable H 2 gas sensor. Image 1 • Quasi-1D WO 3 nanospindles were synthesized by facile hydrothermal method. • P-type PdO with strong catalytic ability to H 2 was loaded on n-type WO 3 nanospindles. • The sensor based on n-WO 3 /p-PdO heterostructure was fabricated. • Towards H 2 , the detection limit of the sensor is 1 ppm, within 9 s. • The H 2 gas sensor shows good stability. [ABSTRACT FROM AUTHOR]

The NiO films were prepared on GaN substrate by depositing an InN epilayer on GaN by plasma-assisted molecular beam epitaxy (PAMBE) and then growing NiO films on InN epilayer by radio frequency (rf) magnetron sputtering. We studied the effect of InN epilayers on structure, surface morphology, electrical and optical properties of NiO films using X-ray diffraction (XRD), scanning electron microscopy (SEM), Hall and optical absorption measurement. It was found that the NiO films grown with InN epilayer exhibited better crystalline qualities with more coalescent surface morphologies and an enhancement of the electrical properties. Moreover, the effect of vacuum annealing on the crystalline qualities of the NiO films was also investigated. [ABSTRACT FROM AUTHOR]

InN epilayers were deposited on nitrided sapphire substrates using plasma-assisted molecular beam epitaxy (PAMBE) system. The physical properties of InN films under different growth temperatures were thoroughly studied. The XRD results indicated that as-prepared InN films without Indium droplets were preferentially oriented in the c-axis direction. The SEM results showed that the InN films grown in a two-dimensional mode with a thickness of ∼200 nm under the growth temperature of 460 °C. In addition, the optical absorption measurement exhibited that the energy bandgap of InN films was around 0.75–0.81eV and the PL spectra of the epilayers revealed an infrared emission. Moreover, the electrical properties of the films were discussed by Hall effect in detail. [ABSTRACT FROM AUTHOR]

InN epilayers were prepared on c -plane (0001) sapphire substrates by plasma-assisted molecular beam epitaxy (PAMBE). We studied the effect of nitridation on structure, surface morphology, electrical and optical properties of InN films using X-ray diffraction (XRD), Reflection high-energy electron diffraction (RHEED), scanning electron microscopy (SEM), atomic force microscopy (AFM), Hall and photoluminescence (PL) measurement. The results showed a significant improvement of the crystalline qualities and surface morphologies and enhancement of the electrical and optical properties for InN films grown after nitridation. Moreover, the energy band-gap of InN films were also determined by optical absorption and photoluminescence (PL) measurement. [ABSTRACT FROM AUTHOR]

Abstract: We report the growth of atomically smooth N-polar GaN on c-plane sapphire by metalorganic vapor phase epitaxy. A two-step growth technique was adopted; low-temperature growth of GaN buffer before high-temperature GaN growth. The complete two-dimensional N-polar GaN growth process was recorded by in situ reflectance. The phase composition of the low-temperature GaN was examined by X-ray diffraction pole figure measurements. The thickness of the low-temperature GaN buffer dramatically affected the crystalline and electronic properties of the N-polar GaN. A very small full width at half maximum for the (0002) X-ray rocking curve, 51arcs, was obtained for 700-nm-thick N-polarity GaN by optimizing the buffer thickness. [Copyright &y& Elsevier]

Abstract: Several series of phthalocyanines (Pcs) and metallophthalocyanines (MPcs) were prepared and characterized by MS, 1H NMR, UV–vis and elemental analysis, which were consistent with the proposed structures. These Pcs and their metal complexes are synthesized using 3-(2-isopropyl-5-methylphenoxyl)phthalonitrile or 4-(2-isopropyl-5-methylphenoxyl)phthalonitrile as the starting material in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU) as the catalyst. An original UV–vis absorption investigation of these compounds is performed. Obvious hypochromic effect of Q-bands was found with the increment of temperature from 293K to 333K. B-bands did not show the analogous tendency. The hypochromic effect originates from conversion of Pc framework as a result of thermal vibration, which reduces the localization of π-electron system. [Copyright &y& Elsevier]

Abstract: Zinc oxide (ZnO) thin film was grown on CaF2 (11–21) substrate by metalorganic vapor phase epitaxy (MOVPE) and the structure, surface morphology and the opto-electrical properties of the film were investigated. It was found that preferential c-axis oriented ZnO film was highly transparent and quite smooth. In photoluminescence (PL) spectrum at 10K, the neutral donor bound exciton (D0X) emission was identified at 3.362eV (I4), the neutral acceptor bound exciton (A0X) emission at 3.346eV (I9). Free A- and B-exciton emissions at 3.374eV and 3.386eV, respectively, as well as the phonon replicas of free A-exciton and D0X were also observed, indicating high optical quality of the ZnO film. Temperature-dependent PL spectra demonstrated that the free exciton emission was dominant at a temperature larger than 215K. Hall measurement showed that the ZnO/CaF2 film exhibited n-type conduction, with the resistivity of 114Ωcm and the Hall mobility of 15.7cm2/Vs. [Copyright &y& Elsevier]

β gallium oxide (β-Ga 2 O 3) homoepitaxy films were grown on (2 ‾ 01) β-Ga 2 O 3 substrates by metal organic chemical vapor deposition (MOCVD). The effect of growth temperature on the crystalline quality was measured and systematically analyzed. The results showed the growth temperature played an important role in crystalline quality of β-Ga 2 O 3. The optimized single crystalline β-Ga 2 O 3 film was grown at 750 °C, and the full width at half maximum (FWHM) of X-ray diffraction (XRD) rocking curve was 21.6 arcsec, smaller than that of the β-Ga 2 O 3 substrate (26.3 arcsec). The film exhibited a greatly smooth surface and the root-mean-square (RMS) roughness was 0.68 nm. And the arrangement of atoms inside the film was in good accordance with lattice constants of β-Ga 2 O 3. In addition, the effect of the band structure on the luminescent properties of β-Ga 2 O 3 was discussed. • The crystalline quality of the optimized film was superior to that of the substrate. • Atomic arrangement inside the β-Ga 2 O 3 films was displayed. • The effect of band structure on the luminescent properties of β-Ga 2 O 3 was discussed. [ABSTRACT FROM AUTHOR]