Boron Nitride Thin Films Grown on Graphitized 6H–SiC Substrates by Metalorganic Vapor Phase Epitaxy

概要

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The growth of thin boron nitride (BN) films on graphitized 6H–SiC substrates was investigated in an attempt to reduce the large lattice mismatch between 6H–SiC and BN, which would improve the three-dimensional ordering in BN thin films grown by metalorganic vapor phase epitaxy (MOVPE). BN thin films were grown by low-pressure (300 Torr) MOVPE using triethylboron and ammonia on graphitized 6H–SiC substrates with surfaces displaying ($1\times 1$) reconstruction as determined by low energy electron diffraction (LEED). The ($1\times 1$) surfaces were formed by annealing at 1500 °C in ultrahigh vacuum with a base pressure of $10^{-10}$ Torr. The LEED patterns showed that the surfaces were covered with single-crystal graphite several monolayers thick. X-ray diffraction revealed that the $c$-axis lattice constant of the BN was 6.72 Å, which is close to the 6.66 Å of bulk hexagonal BN. In contrast, BN films grown on non-graphitized 6H–SiC substrates by MOVPE under the same conditions were mostly amorphous. Use of a graphitized 6H–SiC substrate covered with graphite several monolayers thick improves the degree of three-dimensional ordering in BN thin films grown by MOVPE.
2007-04-30