Showing papers on "Wurtzite crystal structure published in 1976"

Heterojunction band discontinuities

Abstract: The discontinuity ΔEc=0.56 eV in the conduction band edge at n‐CdS/p‐InP junctions is reported. This discontinuity and others are compared with photoemission data and with Van Vechten’s extension of these data to many tetrahedrally coordinated semiconductors. Agreement between measured discontinuities and theoretical predictions is very good. Predictions are made for band parameters pertinent to interfaces involving AIIBIVCV2 compounds with zinc blende, chalcopyrite, or wurtzite crystal structures.

Atomic geometry of cleavage surfaces of tetrahedrally coordinated compound semiconductors

Abstract: Analyses of low‐energy electron diffraction intensities are utilized to determine the surface atomic geometries of GaAs(110), ZnO(1010), and ZnO(1120). The geometry of GaAs(110) is rippled, with the As atoms protruding upwards and the Ga atoms downwards relative to the truncated bulk (zincblende) geometry in a fashion such that no nearest‐neighbor bond lengths are altered. The geometries of ZnO(1010) and ZnO(1120) are nearly those of the truncated bulk (wurtzite) lattice. Small contractions of the upper‐layer spacings of both the oxygen (Δd=−0.1 A) and the zinc (Δd=−0.3 A) sublattices appear probable, however, for ZnO(1010). The qualitatively different nature of the surface reconstruction on GaAs(110) from those which may occur on ZnO(1010) is interpreted in terms of the covalent character of the bonding in GaAs as contrasted with a more ionic bonding in ZnO. Both types of surface reconstruction are consistent with a model in which the cation‐to‐anion charge transfer in the surface layer is less than in the bulk.

Growth of CdS smoke particles prepared by evaporation in inert gases

Abstract: Cds particles, which were prepared in He, Ne, Ar, and Xe gases at pressures of 5–150 Torr, were studied by electron microscopy. Crystals with wurtzite structure grew in single hexagonal plates or prisms or in a more complicated form composed of three or more hexagonal prisms. The mean size of the particles was larger if they were prepared in a heavier gas, and increased almost linearly with gas pressure up to a saturation pressure which was lower for heavier gasses. The particle size distributions in the smokes and the temperature distributions in the chamber are presented for various atmospheres, and on these bases the growth of the particles is discussed.

A Hexagonal (Wurtzite) Form of Silicon

Abstract: The existence of a hexagonal (wurtzite) form of silicon, similar to that form of diamond (carbon) observed in meteorites and in the laboratory, has been identified by x-ray diffraction in reaction-bonded silicon nitride containing unreacted silicon. The presence of this phase is due to stresses created in the silicon by the nitridation reaction.

The crystal structure of 2,5-dimercaptothiadiazole

Abstract: compounds be discussed but also the deviations of the structures from the cubic symmetry found with inorganic cations. With the amino acid, Te atoms are at the apex of an A face-centred monoclinic lattice. The contacts between Br atoms in different anions range from 3.943 to 4.134 A, which are larger than van der Waals contacts. With the succinamide, Te atoms are 0-515 A away from the apex of the C face-centred lattice. The van der Waals contacts between Br atoms in different TeBr6 aions are grouped into four short contacts of 3.705 and two longer contacts of 3.953 A. A larger organic cation tends to distort the octahedra network but does not deform it fundamentally. In the two structures, the cohesion is governed by hydrogen bonds and Br . . -Br intermolecular van der Waals contacts. The packing of the molecules approaches close packing, with the octahedra in contact, and the cavities occupied by the organic cations.

Optical filters using coupled light waves in mixed crystals

Abstract: Coupling of polarized optical waves in wurtzite II‐VI mixed crystals is studied. It is shown that these crystals provide narrow‐band optical filters over a wide spectral range.