Growth of SiC thin films on SOI substrates by RTCVD

This project was primarily aimed at determining the result of growing SiC on SOI substrates with a device layer thickness approaching that of the overgrown film. The major portion of this study was devoted to optimize the carbonization of the Si device layer and to attempt to completely carbonize the Si layer to SiC.; Both bonded and the SIMOX varieties of SOI were used in the growth experiments, all of which were performed in a Rapid Thermal CVD system. The effects of numerous processing parameters such as growth temperature, growth time, gas flow rate, substrate orientation, and temperature ramp rate on the SiC layer were studied using SEM, FTIR, XRD, SIMS, TEM, AFM, RHEED, and Raman spectroscopy.; The results indicated that the Si that converts to SiC comes mainly from select locations in the device layer which later coalesce to form voids. This void phenomenon prevents realization of the concept of completely converting the Si device layer to SiC.; Our results prove that the SiC films grown on the SOI substrates can be made to be of equal quality to that grown on regular Si substrates. However, complete conversion of the Si device layer appears difficult at this time and no compliant layer effect was observed.; Thicker SiC layers were deposited by thermally decomposing trimethylsilane which is an organic molecule containing both Si and C atoms. A range of process parameters was explored.; The second part of this project comprised growth of GaN on the SiC/SOI substrates and evaluation of the films.; GaN was grown on the 3C SiC deposited on Si as well as on SOI substrates. This approach can enable one to grow very thick GaN layers on the SOI structure, and then easily remove the substrate by chemically etching the oxide "release" layer.; As part of a collaboration with Dr. C. Tran of Emcore Inc., Metalorganic CVD growth of GaN layers on the (111) SiC SOI structures was carried out in a stainless steel, rotating disk reactor with trimethylgallium and NH{dollar}sb3{dollar} precursors at 1000{dollar}spcirc{dollar}C for 1 hour, producing {dollar}sim{dollar}2 {dollar}mu{dollar}m films. Encouraging structural and optical properties were obtained from the GaN layers.; The SiC carbonization conditions were seen to strongly influence the GaN PL characteristics, with the fully converted SiC layers resulting in a quenching of the yellow band emission and an enhancement of the UV emission. Our studies also showed reasonably good PL uniformity across a one inch surface of GaN grown on 3C SiC/Si.; In conclusion, we have shown that SiC SOI structures obtained by carbonization have the potential to serve as useful substrates for GaN growth. (Abstract shortened by UMI.)...