Structural properties of the nitride-on-silicon microdisks.
(a) Schematic view of a microdisk. The structure is composed of an AlN disk with twenty GaN/AlN quantum wells (0.7 nm quantum well – 5 nm barrier), maintained by a silicon post on a silicon substrate; the distribution of the electric field intensity of a WGM is illustrated on the top of the disk, as calculated for a TE mode in a 2 μm-diameter microdisk (radial order n = 1, azimutal order m = 33, vertical confinement number q = 1). As indicated by arrows, the microdisk is excited at normal incidence by the pump laser and the emission is collected from the edge. (b) Transmission Electron Micrograph (TEM) of the GaN/AlN quantum wells. (c) Scanning Electron Micrograph (SEM) of a 8 μm-diameter microdisk. (d) Atomic Force Micrograph of the AlN buffer layer.