Aluminophosphate glasses and quasi-amorphous nitrides - a step in the quest for photonic materials

Summary form only given. We present a review of the research carried out during the past six months by groups from Romania, Victoria University of Wellington, New Zealand, and Universite de Provence, Marseille, France, with the aim to fabricate photonic materials within the framework of the COST ACTION P11. Novel aluminophosphate glasses doped with semiconductors (CdSSe) have been produced, whose transmission in the visible and Raman spectra have been investigated. We have noticed that transmission edge and the spectra shape depend on the crystallites´ dimensions. The fluorescence is relatively narrow (0.12-0.15 eV) suggesting reasonably well-ordered crystallites with reasonably uniform diameters. Another attempt of the groups to find a way of producing quasi-periodic, at this stage, features, in amorphous materials, consists of annealing studies on amorphous GaN thin films (150 nm) on silicon. The annealing processes have been carried out using the hot stage of an electronic microscope (SEM), so that real time observation has been possible. Following the annealing, the GaN films have developed hemispherical structures uniformly distributed over the entire surface of the sample. Apparently, those structures are denser than the surrounding film, and EDX analysis shows that they conserved the initial composition of the film. At the necked eye the colour of the sample changed from blue to yellow.