Carbonized Ultrathin Si on SiO2 (SICOI): A Compliant Substrate for Growth of Epitaxial GaN and AlN

Phase I proposes to fabricate low-defect, high-quality silicon carbide on ultrathin silicon-on-insulator (SOI) structures as a lattice-matched substrate for growth of GaN by atomic layer epitaxy (ALE) . Preliminary results clearly demonstrated superior quality B-SiC grown on ultrathin (about 300A) Si on SiO2, compared to that grown under identical conditions on standard SIMOX (with a thickness of 2000A) or on bulk Si. Transmission electron microscopy (TEM), electron diffraction, and RBS/channeling studies indicated the growth of epitaxial single-crystal SiC on ultrathin Si on Si02 while results from standard SIMOX indicated the growth of polycrystalline SiC and single crystal sic. our results indicate that a uniform and high integrity thin Si top layer is necessary for successful growth of good quality SiC films. During etching of thick SOI, threading dislocation defects are converted to pinholes thus the buried oxide is depleted. We have already demonstrated the fabrication of ultrathin Si, as thin as 140A on SiO2 by using the LES (20 to 30 keV) process to produce low-cost films of excellent integrity compared to thinned commercial SIMOX. Based on these results, ultrathin Si-on-insulator substrates appear to have great potential for producing SiC films suitable as substrates for device quality GaN films.