The Effect of Aluminum Nitride-Silicon Carbide Alloy Buffer Layers on the Sublimation Growth of Aluminum Nitride on SiC (0001) Substrates
The benefits of depositing AlN-SiC alloy transition layers on SiC substrates before the seeded growth of bulk AlN crystals were determined. The presence of the AlN-SiC alloy layer helped to suppress the SiC decomposition by providing vapor sources of silicon and carbon. It enabled a higher growth temperature, and hence a higher growth rate. In addition, cracks in the final AlN crystals can be decreased because of the intermediate lattice constants and thermal expansion coefficient of AlN-SiC alloy. AlN-SiC alloys were first grown on off-axis SiC substrates by the sublimation-recondensation method. Then pure AlN crystals were grown upon those. For comparison, AlN crystals were directly grown on SiC substrates under similar conditions. X-ray diffraction (XRD) confirmed the formation of a pure single crystalline AlN layer upon the AlN-SiC alloy on SiC substrate. The presence of an AlN-SiC transition layer effectively inhibited the appearance of cracks in the resultant AlN crystals. X-ray topography (XRT) demonstrated that the thick AlN layer effectively released the strain present.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
Z. Gu et al., "The Effect of Aluminum Nitride-Silicon Carbide Alloy Buffer Layers on the Sublimation Growth of Aluminum Nitride on SiC (0001) Substrates ", Materials Science Forum, Vols. 527-529, pp. 1497-1500, 2006