Papers by Keyword: Orientation Dependency

Abstract: (001)-, (1110), and (105)- oriented SrBi4Ti4O15 films with its c-axis tilted 0, 45 and 55o from the surface normal were epitaxially grown by metal organic chemical vapor deposition and the temperature dependency of the dielectric constant was systematically investigated. Relative dielectric constant, εr, and its temperature dependency increased when the tilting angle of the c-axis from the substrate surface normal increased. Temperature dependency of εr was positive in case of the (105) and (1110) orientation, which is in good agreement with the conventional ferroelectric materials. On the other hand, it became negative for (001) orientation. This shows the orientation dependency of εr in SrBi4Ti4O15.

Abstract: The defect distribution in 4H-SiC single crystals in dependence on the seed polarity and its off-orientation was investigated by KOH-etching, optical microscopy and X-ray topography. Micropipe density, stacking fault density and dislocation density were determined for 2” crystals grown in <000-1> direction 0 - 7° off towards <11-20> and for crystals up to 1” in diameter grown in <11-20> or a- and <1-100> or m-directions and using repeated a-face growth. For the growth in polar directions the micropipe density and dislocation density decrease with increasing offorientation of the seed. A similar behavior was found for the stacking fault density and dislocation density in non-polar directions with off-orientation to c-direction. Nevertheless, while the dislocation density could be reduced up to three orders of magnitude for the growth along non-polar directions, the stacking fault density was continuously increasing. Additionally, the defect distribution after repeated a-face growth will be discussed in terms of growth related and kinetic models.