H. M. Yates

Face centered cubic photonic bandgap materials based on opal-semiconductor composites

We discuss photonic crystal properties of semiconductor-opal composites and explore the possibility of using these structures as photonic bandgap (PEG) materials in the visible and near-infrared region of the spectrum. Integrated reflectance in the optical region is used to show that the photonic crystal behavior of InP opal is enhanced with respect to the bare matrix as a result of the new refractive index contrast. Order-N band structure and transfer matrix calculations have proved to be in good agreement with the experiments. In addition, a strong coupling effect has been observed between CdS photoluminescence and the photonic structure, which leads to a partial inhibition of the spontaneous emission.

Controlling the sulphur content of ZnSe1−ySy epitaxial layers grown by metalorganic chemical vapor deposition using diethyl selenide, hydrogen sulphide, and dimethylzinc

Epitaxial layers of ZnSe1−ySy on (100) GaAs substrates have been grown by metalorganic chemical vapor deposition. The reactants used are dimethylzinc (DMZn), hydrogen sulphide (H2S) and diethylselenide (DESe). The DESe has been used rather than the more usual selenium precursor, hydrogen selenide (H2Se). Results on the relationship between the sulphur incorporated into the epilayer and the group VI gas phase reactant molar ratio show a more linear relationship than previously found for the atmospheric pressure growth of this material using the hydrides. Despite the higher growth temperature (450u2009°C) and nonoptimized conditions the epilayers are shown to be comparable with those grown with hydrides and at lower growth temperatures (280u2009°C). Low‐temperature (10 K) photoluminescence gave near‐band‐edge emission linewidths of 6.8 meV for the ZnSe0.87S0.13 ternary.

Structural and compositional integrity of lattice‐matched ZnSe0.95S0.05 on (100) orientated GaAs

Lattice‐matched ZnSe0.95S0.05 epitaxial layers have been grown on (100)u2009oriented GaAs substrates by atmospheric pressure metalorganic vapor phase epitaxy. Blue room‐temperature photoluminescence is observed and the interface is both compositionally and structurally abrupt as shown by secondary ion mass spectrometry and high‐resolution transmission electron microscopy.

Metal Organic Chemical Vapour Deposition Growth of Epitaxial ZnSe/ZnS Multiple Layered Structures

ZnSe-ZnS multilayers have been prepared by atmospheric. pressure metal organic chemical vapour deposition (M0CVD) using dimethylzinc, hydrogen sulphide and hydrogen selenide. Layer thicknesses down to 500A have been obtained and the interfaces, as measured by secondary ion mass spectroscopy (SIMS) and electron microscopy, are regular. A notable improvement in interface abruptness was observed with better control of experimental procedures and more especially with the growth of a ZnSe buffer layer between the GaAs(100) substrate and multilayers.

Thin-film coated opals-an approach to 3-dimensional photonic crystals

Summary form only given. Synthetic opal provides a 3D template for the formation of photonic crystals for visible light operation. Improvement of the photonic bandgap structure of opal has been approached via coating the inner surface of the opal with TiO/sub 2/, InP or GaP layers using CVD and MOCVD. In contrast to other methods of embedding high refractive index materials in opal these methods allow the crystallinity of the original template to be preserved. The high refractive index coating serves to increase the width of the photonic stop-band and to squeeze the angular dispersion of the stop-band.