The formation of basal plane stacking faults in heavily nitrogen-doped 4H-SiC crystals was theoretically investigated. A novel theoretical model based on the so-called quantum well action mechanism proposed; considers several factors, which were overlooked a previously proposed model, and provides detailed explanation annealing-induced double layer Shockley-type crystals. We further revised to consider carrier distribution depletion regions adjacent fault successfully explained shrinkage...

The etching mechanism of SiC single crystals by molten KOH has been investigated. process is significantly affected the ambience: rate greatly reduced a nitrogen gas purge. This result clearly suggests an essential role dissolved oxygen in melt. SiC{0001} surfaces show large surface polarity dependence, where SiC(0001)C about four times larger than that SiC(0001)Si. exhibits Arrhenius type temperature dependence with activation energy 15–20 kcal/mol. obtained and selectivity between (0001)C...

Micro-Raman imaging measurements of $n$-type $4H\text{\ensuremath{-}}\mathrm{Si}\mathrm{C}$ crystals with graded donor concentration were carried out, and spatial distributions the free carrier concentration, mobility, longitudinal optical (LO) phonon damping obtained from a line shape analysis LO phonon-plasmon coupled (LOPC) mode. The carriers optic phonons was determined as function density. We an empirical relationship between relative Raman shift LOPC mode, which is in close agreement...

Raman spectra of 6H-SiC crystals including stacking faults have been examined for the c face using backscattering geometry. The intensity transverse optical phonon band at 796 cm−1, which corresponds to mode Γ point in 3C-SiC, is sensitive faults. We found that this depends on fault density. This explained based bond polarizability model. spatial distribution studied by image measurement.

This study has concentrated on the sublimation growth of SiC in directions perpendicular to c-axis. 6H- and 4H-SiC crystals are grown [11-00] [112-0] by modified-Lely method. The different many aspects from those conventional 〈0001〉 directions. polytypic structure perfectly succeeds that seed, thus polytype mixing never occurs. contain no hollow core dislocations (micropipes) exhibit a characteristic strain relaxation. A number stacking faults basal plane introduced during growth, density...

The formation of single Shockley stacking faults (SSSFs) in 4H-SiC crystals under non-equilibrium conditions (e.g., the forward biasing PiN diodes and ultraviolet light illumination) is a key phenomenon so-called bipolar degradation SiC power devices. This study theoretically investigated physical mechanism this based on concept quantum well action. As first approximation describing state material, we employed quasi-Fermi level approximation. We then made improvements by considering several...

We observe a significant reduction of threading dislocations in GaN grown on vicinal substrates SiC(0001). Using scanning tunneling microscopy, we find films maintain the surface misorientation substrate and display terraces with straight edges. On top there is no spiral mound, which main feature found for singular substrates. Transmission electron microscopy studies confirm that screw are reduced by two orders magnitude while edge one order.

ST0753, the orthologous gene of Type 1 RNase H found in a thermoacidophilic archaeon, Sulfolobus tokodaii, was analyzed. The recombinant ST0753 protein exhibited activity both vivo and vitro assays. expressed an H-deficient mutant Escherichia coli strain functioned to suppress temperature-sensitive phenotype associated with lack H. characteristics gene's were similar those Halobacterium HI, first archaeal be characterized. Surprisingly, S.tokodaii HI cleaved not only RNA strand RNA/DNA...

Escherichia coli RNase HII is composed of 198 amino acid residues. The enzyme has been overproduced in an insoluble form, purified a urea-denatured and refolded with poor yield [M. Itaya (1990) Proc. Natl. Acad. Sci. USA 87, 8587-8591]. To facilitate the preparation amount sufficient for physicochemical studies, we constructed overproducing strain which E. produced soluble form. was from this its biochemical properties were characterized. good agreement molecular weights estimated SDS-PAGE...

We report on the observation of impurity-induced morphological instability step trains during sublimation growth $6H\ensuremath{-}\mathrm{SiC}(0001).$ $6H\ensuremath{-}\mathrm{SiC}(0001)$ provides a system suitable for studying effects repulsive interaction. Its large height and stiffness result in strong repulsion force between steps, which energetically establishes extremely regular equidistant surface. Upon nitrogen doping, these become unstable: are transformed into meandering macrosteps...

Nitrogen incorporation kinetics during the sublimation boule growth of SiC have been studied in terms several parameters. 6H and 4H crystals were heavily doped with nitrogen as a donor. It was found that rate has little influence on doping concentration, indicating is not kinetically limited at normal rates growth. On other hand, surface polarity polytype to front. By optimizing conditions, bulk resistivities low 7.6×10 -3 Ω cm 5.3×10 obtained for SiC, respectively.

4H-SiC single crystals were grown by the physical vapor transport (PVT) growth method under different thermoelastic stress conditions, and degree of basal plane bending in was characterized peak shift measurement X-ray rocking curves. The results indicate that largely depends on magnitude stresses imposed during PVT growth. Quantitative analysis revealed density dislocations (BPDs) estimated from is much smaller than obtained defect-selective etching. It also found BPD correlated with...

In low energy scanning electron microscope (SEM) with primary less than 1.0 keV, the dependence of SEM contrast on crystallographic orientation within a range nm in depth has been investigated by utilizing 4H-SiC (0001) as standard sample having definitive penetration marker layer at hexagonal sites. Reflecting difference direction topmost two Si-C bilayers stacking sequence (0.50 depth), clear bright and dark observed adjusting tilting rotation angles conventional Everhart–Thornley type...