2 research outputs found
Gallium Nitride Based Logpile Photonic Crystals
We demonstrate a nine-layer logpile three-dimensional photonic crystal (3DPC) composed of single crystalline gallium nitride (GaN) nanorods, ∼100 nm in size with lattice constants of 260, 280, and 300 nm with photonic band gap in the visible region. This unique GaN structure is created through a combined approach of a layer-by-layer template fabrication technique and selective metal organic chemical vapor deposition (MOCVD). These GaN 3DPC exhibit a stacking direction band gap characterized by strong optical reflectance between 380 and 500 nm. By introducing a “line-defect” cavity in the fifth (middle) layer of the 3DPC, a localized transmission mode with a quality factor of 25–30 is also observed within the photonic band gap. The realization of a group III nitride 3DPC with uniform features and a band gap at wavelengths in the visible region is an important step toward realizing complete control of the electromagnetic environment for group III nitride based optoelectronic devices
Nonpolar InGaN/GaN Core–Shell Single Nanowire Lasers
We report lasing from nonpolar p-i-n
InGaN/GaN multi-quantum well core–shell single-nanowire lasers
by optical pumping at room temperature. The nanowire lasers were fabricated
using a hybrid approach consisting of a top-down two-step etch process
followed by a bottom-up regrowth process, enabling precise geometrical
control and high material gain and optical confinement. The modal
gain spectra and the gain curves of the core–shell nanowire
lasers were measured using micro-photoluminescence and analyzed using
the Hakki-Paoli method. Significantly lower lasing thresholds due
to high optical gain were measured compared to previously reported
semipolar InGaN/GaN core–shell nanowires, despite significantly
shorter cavity lengths and reduced active region volume. Mode simulations
show that due to the core–shell architecture, annular-shaped
modes have higher optical confinement than solid transverse modes.
The results show the viability of this p-i-n nonpolar core–shell
nanowire architecture, previously investigated for next-generation
light-emitting diodes, as low-threshold, coherent UV–visible
nanoscale light emitters, and open a route toward monolithic, integrable,
electrically injected single-nanowire lasers operating at room temperature