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《International Journal of Hydrogen Energy》2019,44(36):19650-19657
To split water and produce hydrogen by white light is an excellent solution for the storage and supply of clean and sustainable energy. Efficiency and stability are the key challenges for a successful exploitation. InGaN, evaluated against other semiconductors, metal oxides, carbon based - and organic materials has most suited intrinsic materials properties. Based on this optimum materials choice we report photoelectrochemical (PEC) hydrogen generation under white light illumination by an InGaN-based quantum nanostructure photoelectrode. No degradation occurs for operation over 10 h. Our novel concept, combining quantum nanostructure physics with electrochemistry and catalysis leads to almost 10% efficiency at zero external voltage. The efficiency rises above 25% at 0.2 V. This is unmatched for a single photoelectrode, representing the most advanced technology of low complexity. 相似文献
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量子点中的应变场分布对量子点的力学稳定性、压电性能以及光电性能有着重要的影响。基于有限元方法,并考虑了InN/GaN材料的六方纤锌矿结构特性,分别对透镜形、平顶六角金字塔形和六角金字塔形量子点的应变分布进行了比较,结果表明应变主要集中在浸润层和量子点内,在讨论量子点中电子能级时必须考虑浸润层的影响。量子点内的应变分布及静水应变和双轴应变受几何形状的影响明显。此外还计算了三种形状量子点的总能量,六角金字塔形量子点总能量最小,而透镜形量子点总能量最大,因此六角金字塔形是最稳定的结构,而透镜形是最不稳定的结构。 相似文献
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InN film was grown on 4H-SiC (0001) substrate by RF plasma-assisted molecular beam epitaxy (RF-MBE). Prior to the growth of InN film, an InN buffer layer with a thickness of ~ 5.5 nm was grown on the substrate. Surface morphology, microstructure and structural quality of InN film were investigated. Micro-structural defects, such as stacking faults and anti-phase domain in InN film were carefully investigated using transmission electron microscopy (TEM). The results show that a high density of line contrasts, parallel to the growth direction (c-axis), was clearly observed in the grown InN film. Dark field TEM images recorded with diffraction vectors g = 1120 and g = 0002 revealed that such line contrasts evolved from a coalescence of the adjacent misoriented islands during the initial stage of the InN nucleation on the substrate surface. This InN nucleation also led to a generation of anti-phase domains. 相似文献
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The carrier cooling and the carrier relaxation of an InN thin film illuminated with two excitation energies of 1.53 and 3.06 eV were studied by an ultrafast time-resolved photoluminescence upconversion apparatus. The hot phonon effect could be accounted for longer effective phonon emission times as compared to the theoretical prediction. The rise time and the LO phonon emission time for 3.06 eV excitation were much smaller than those for 1.53 eV excitation. These differences were attributed to the intervalley scattering between the Γ1 and Γ3 valleys in InN when carriers were excited with the energy of 3.06 eV. The intervalley scattering times of 250 fs and 2 ps were estimated for the intervalley scattering from the Γ1 to Γ3 valley and the reversed scattering process, respectively. 相似文献
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100 nm InN layer was grown on sapphire c-plane using a metal-organic chemical vapor deposition (MOCVD) system. Low temperature (LT) GaN layer was grown on InN layer to protect InN layer from direct exposure to hydrogen flow during high temperature (HT) GaN growth and/or abrupt decomposition. Subsequently, thick HT GaN layer (2.5 μm thick) was grown at 1000 °C on LT GaN/InN/sapphire template. Microstructure of epilayer-substrate interface was investigated by transmission electron microscopy (TEM). From the high angle annular dark field TEM image, the growth of columnar structured LT GaN and HT GaN with good crystallinity was observed. Though thickness of InN interlayer is assumed to be about 100 nm based on growth rate, it was not clearly shown in TEM image due to the InN decomposition. The lattice parameters of GaN layers were measured by XRD measurement, which shows that InN interlayer reduces the compressive strain in GaN layer. The relaxation of compressive strain in GaN layer was also confirmed by photoluminescence (PL) measurement. As shown in the PL spectra, red shift of GaN band edge peak was observed, which indicates the reduction of compressive strain in GaN epilayer. 相似文献
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TEM study of indium and gallium nitride nanocrystals in silica gasses obtained by the sol-gel method
GaN and InN nanocrystals in silica glasses prepared by the sol‐gel method were studied by transmission electron microscopy techniques. Morphology, structure and phase composition of silica gel containing Ga or In as function of the calcination and nitridation temperature were investigated. 相似文献
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V. Ya. Malakhov 《Solar Energy Materials & Solar Cells》2003,76(4):637-646
The fabrication details, as well as basic structural and optical properties, of low temperature plasma enhanced reactively sputtered InN thin films are presented. SEM and AFM studies of surface morphology, including a microstructural cross-section were performed. Optical absorption and reflectance spectra of InN textured films at room temperature in the visible and NIR regions were taken, to reproduce accurately the dielectric function as well as to determine the optical effective mass of electrons (0.11) and the direct band gap (2.03 eV). Some TO (445, 480 and 490 cm−1) and also LO (570 cm−1) phonon features of indium nitride polycrystalline films in the near infrared and Raman spectra are presented and discussed.These results, both as obtained now and a few years ago from identical samples just after preparation, are in good agreement. This demonstrates an extraordinary long-term stability of this compound, with respect to its optical and electrical characteristics. The attractive possibilities based on model calculations of InN/Si tandem film systems for potential applications in photovoltaic devices, including high efficiency thin film solar cells, are emphasized and discussed. 相似文献
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S. M. Donovan J. D. Mackenzie C. R. Abernathy S. J. Pearton P. C. Chow J. Van Hove 《Journal of Electronic Materials》1997,26(11):1292-1296
The effects of growth temperature and nitrogen plasma biasing on the electrical and structural properties of InN grown using
electron cyclotron resonance metalorganic molecular beam epitaxy (ECR MOMBE) have been investigated. These results are compared
to those found from InN grown using a higher energy radio frequency (rf) plasma source (rf MOMBE). By varying the bias of
the nitrogen plasma or the growth temperature, it is possible to achieve smooth surface morphologies. However, biasing can
also be used to increase the mobility by a factor of two while the growth temperature has only a small effect. By contrast,
use of an rf plasma improves mobility by nearly a factor of ten. None of the growth conditions investigated were found to
significantly alter the electron concentration, which was measured to be 1−5 × 1020 cm−3. 相似文献