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The silicon to carbon precursor ratio was found to strongly influence the spontaneous nucleation of cubic SiC upon the growth of epitaxial layers of 4H and 6H silicon carbide utilizing the chemical vapor deposition (CVD) method. High C/Si ratios apparently enhance the nucleation of cubic SiC. A model of CVD process chemistry that relates the effect to a decrease of SiC surface mobility with an increase of the C/Si ratio is suggested. The resulting rise in supersaturation at the surface terraces induces the spontaneous nucleation of cubic SiC.

By carefully controlling the surface chemistry of the chemical vapor deposition process for silicon carbide (SiC), 100 μm thick epitaxial layers with excellent morphology were grown on 4° off-axis SiC substrates at growth rates exceeding 100 μm/h. In order to reduce the formation of step bunching and structural defects, mainly triangular defects, the effect of varying parameters such as growth temperature, C/Si ratio, Cl/Si ratio, Si/H2 ratio, and in situ pre-growth surface etching time are studied. It was found that an in-situ pre growth etch at growth temperature and pressure using 0.6% HCl in hydrogen for 12 min reduced the structural defects by etching preferentially on surface damages of the substrate surface. By then applying a slightly lower growth temperature of 1575 °C, a C/Si ratio of 0.8, and a Cl/Si ratio of 5, 100 μm thick, step-bunch free epitaxial layer with a minimum triangular defect density and excellent morphology could be grown, thus enabling SiC power device structures to be grown on 4° off axis SiC substrates. [ABSTRACT FROM AUTHOR]

Using various junction space-charge techniques, annealing, and simulation, a metastable defect in 6H SiC have been characterized. We suggest a configuration coordinate diagram with three configurations, where two of them can only exist when the defect is occupied by one or more electrons. The thermal ionization energies for the different configurations were measured and the thermal barriers for two of the transitions have been determined. It is also shown that the transformation process is governed by electron capturing to the defect. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study which examined the collection of cross sections electron irradiation induced deep levels in silicone carbide 6H-SiC p+n diodes. Methods used to conduct the study; Identification of the physical and electronic properties of silicon carbide; Indication that intrinsic defects are found in semiconductors; Results and discussion on the study.

Deep level defects in electron-irradiated 4H SiC epitaxial layers grown by chemical vapor deposition were studied using deep level transient spectroscopy. The measurements performed on electron-irradiated p+n junctions in the temperature range 100-750 K revealed several electron traps and one hole trap with thermal ionization energies ranging from 0.35 to 1.65 eV. Most of these defects were already observed at a dose of irradiation as low as ≈ 5 × 10[sup 13] cm[sup -2]. Dose dependence and annealing behavior of the defects were investigated. For two of these electron traps, the electron capture cross section was measured. From the temperature dependence studies, the capture cross section of these two defects are shown to be temperature independent. [ABSTRACT FROM AUTHOR]