Showing papers by "Tsunenobu Kimoto published in 1993"

Growth mechanism of 6H-SiC in step-controlled epitaxy

Abstract: Growth of SiC on off‐oriented 6H‐SiC{0001} substrates was performed between 1100 and 1500 °C. Homoepitaxial growth of 6H‐SiC was achieved at temperatures as low as 1200 °C, utilizing step‐flow growth. Twinned crystalline 3C‐SiC was grown at 1100 °C; this result can be ascribed to suppressed surface migration of adsorbed Si species at the lower temperature, and to the occurrence of two‐dimensional nucleation on terraces. The C/Si ratio significantly effected the surface morphology and growth rate. The growth rate was limited by the supply of Si species, where the growth rate activation energy was very small (3.0 kcal/mol), and little difference in the growth rates on Si and C faces was observed. The quantitative analysis revealed that growth of 6H‐SiC in step‐controlled epitaxy is controlled by the diffusion of reactants in a stagnant layer.

Step-Controlled Epitaxial Growth of 4H-SiC and Doping of Ga as a Blue Luminescent Center

Abstract: Homoepitaxial growth of 4H-SiC could be achieved at 1500°C on off-oriented 4H-SiC{0001} substrates by means of a vapor phase epitaxial method. Grown layers showed specular smooth surfaces on both (0001)Si and (000)C faces. Doping of Ga during crystal growth was carried out and photoluminescence of grown layers was studied. Bluish-violet photoluminescence due to donor(N)-acceptor(Ga) pair recombination and recombination of a free electron with a hole at a Ga acceptor was observed. The emission attributed to the latter recombination process became dominant at high temperatures above 100 K. The luminescence of Ga-doped 4H-SiC was not quenched up to temperatures as high as 150 K, whereas the luminescence intensity of Al-doped 6H-SiC and 4H-SiC started to decrease at 70 and 85 K, respectively.

4H-SiC/6H-SiC interface structures studied by high-resolution transmission electron microscopy

Abstract: The interface structures of 4H‐SiC/6H‐SiC heterostructures formed in monocrystalline bulk silicon carbide were studied by high‐resolution electron microscopy of cross‐sectional specimens. The samples were grown on the (0001) C face of a 6H‐SiC seed with in situ Ce doping. The observed transition region is atomically flat over regions of several hundreds nm. The transition from the initial 6H‐SiC growth to the 4H‐SiC growth happens all at once at certain thicknesses with the occurrence of only a few layers of 4H‐SiC (6H‐SiC) before (after) the transition. The atomic stacking sequence at the interface of the two polytype crystals can be resolved.