High-Quality ZnO Layers Grown on 6H-SiC Substrates by Metalorganic Chemical Vapor Deposition

In this letter, the 6H-SiC substrate has been studied for the growth of the ZnO layer. The X-ray diffraction measurement clearly showed the c-axis oriented growth of ZnO layers on SiC(0001) substrates. The X-ray rocking curve measurement diffracted a smaller full-width at half maximum of the ZnO layers grown on SiC than that of the same layers grown on the conventional Al2O3 substrate with metalorganic chemical vapor deposition (MOCVD). A distinct free-exciton emission was dominantly observed even at room temperature (RT) while the donor-bound-exciton peaks were disappeared at around ∼120 K. In addition, no deep-level emission was observed even at RT in the ZnO/SiC samples. These optical and crystalline properties have hardly been observed in the ZnO/Al2O3 samples grown by MOCVD. Therefore, the higher quality of the ZnO layers grown on SiC might be attributed to the smaller lattice mismatch of ∼5% as well as the +c surface orientation in ZnO/SiC sample geometry.