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High-crystalline-quality epitaxial films of wurtzite AlN were grown by metalorganic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HVPE). The lattice strain of the films was analyzed by high-resolution X-ray diffraction and the E2 (high)-phonon frequency was observed by Raman scattering. Data analysis for wide ranges of lattice strains and phonon-peak shifts yielded a precise biaxial stress coefficient of this phonon mode, -4.04±0.3 cm-1/GPa. Furthermore, the deformation potential constant was accurately determined from the biaxial stress coefficient.

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Biorefinery for the purpose of producing biofuels, chemicals, and materials has received much attention. Furfural alcohol (FOL) and levulinate ester (LE) are important biomassderived platform chemicals, and they are produced from sugar-based furfural (FAL). Unfortunately, the two products are often obtained separately in different reaction systems, which is undesirable; furthermore, it is of significant practical interest to control their selectivity so that the desired product can be accumulated in high yields. Herein, we present an efficient method for the highly selective conversion of FAL to FOL or isopropyl levulinate (IPL) in a one pot system using isopropanol as the hydrogen source and ZrO 2 @SBA-15 as a bifunctional catalyst with both Lewis acid and Brønsted acid sites. Under optimized reaction conditions, high yields of FOL and IPL in up to 90.4% and 87.2%, respectively, were obtained. Based on the experimental results, a kinetic model describing the catalytic conversion of FAL into FOL and IPL process has been established, which has a good correlation (R 2 > 0.92) between the measured and predicted data. The developed kinetics can provide an effective tool to monitor the process and tailor the process conditions to obtain the desired product.

The growth conditions and interface microstructure of AlN on sapphire grown using a nucleation layer (NL) have been studied. The AlN layer with NL-AlN grown at 1100 °C exhibits a smooth surface morphology. The epilayer has a small amount of tilting but the twisting is large. For the AlN layer with NL-AlN grown at 1250 °C, the twisting is reduced, but the surface is rough owing to the mixing of crystallographic polarity. The origins of AlN inversion domains are discussed by considering the microstructures observed by transmission electron microscopy (TEM), with the ultimate aim of growing a high-quality AlN layer.