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Influence of growth rate on homoepitaxial growth of AlN at 1450 °C by hydride vapor phase epitaxy

The influence of growth rate on the homoepitaxial growth of AlN at 1450 °C by hydride vapor phase epitaxy on bulk AlN(0001) substrates was studied. X-ray diffraction and Raman spectroscopy revealed that high structural quality comparable to that of the initial substrate can be achieved even when the growth rate is increased to over 150 μm h−1. Although the concentration of Si impurities increased with increasing growth rate, a freestanding AlN substrate prepared from a homoepitaxial layer grown at 155.6 μm h−1 showed a steep optical absorption edge at 207 nm and high optical transmittance at longer wavelengths.