Metal-organic vapor phase epitaxy for the mass production of novel semiconductor devices

We report on growth results achieved in AIXTRON multiwafer planetary reactors for the growth of phosphide-arsenide and nitride based novel semiconductor structures and devices. In case of the phosphide-arsenide based structures we focused on growth on 6-in GaAs wafers. Ga/sub 0.47/InP layers were grown with standard deviations for the Ga-concentration of 0.75% and 0.3% on wafer and wafer-to-wafer, respectively. We attribute this result to the excellent temperature homogeneity of 1/spl deg/C throughout the reactor. This factor also plays a role in the deposition of nitride-based semiconductors that was investigated for the growth of InGaN multiquantum wells for the blue (472 nm) and green (522 nm) wavelengths. Wafer-to-wafer wavelength distributions of max-min of /spl plusmn/2.1 nm (blue) and /spl plusmn/4.2 nm (green) were achieved. On wafer standard deviations of the wavelength fell in the range of 1.6-1.7 nm, respectively.     

Guest Editorial

Journal of Signal Processing Systems -     

Levels in 44Ca excited by the β-decay of 44K

The β-decay of 22 min ⁴⁴K has been re-investigated with a Ge(Li) spectrometer of improved resolution and efficiency. A total of 58 γ-rays has been assigned to the decay of ⁴⁴K. Of these 53 have been incorporated into a revised decay scheme containing 20 excited states. The ⁴⁴K half-life was determined to be 22.15 ± 0.20 min.     

Regular incidence-polytopes with Euclidean or toroidal faces and vertex-figures

Regular incidence-polytopes are combinatorial generalizations of regular polyhedra. Certain group-theoretical constructions lead to many new regular incidence-polytopes whose faces and vertex-figures are combinatorially isomorphic to classical Euclideanly regular polytopes or regular maps on the torus.     

The existence of non-tiles and non-facets in three dimensions

Non-tiles are convex polytopes, of which isomorphic copies will not tile the space locally finite and face-to-face (that is, neighbouring tiles meet in a face of each). Non-facets are convex polytopes, of which isomorphic copies will not fit together as the facets of a higher dimensional convex polytope. It is proved that there are infinitely many 3-dimensional convex polytopes which are non-tiles as well as non-facets, thereby answering a question of Danzer.     

Eine Formel für schiefsymmetrische bilineare Räume mit vier maximal totalisotropen Unterräumen

Ohne Zusammenfassung