RESUMEN
Light-emitting sources and devices permeate every aspect of our lives and are used in lighting, communications, transportation, computing, and medicine. Advances in multifunctional and "smart lighting" would require revolutionary concepts in the control of emission spectra and directionality. Such control might be possible with new schemes and regimes of light-matter interaction paired with developments in light-emitting materials. Here we show that all-dielectric metasurfaces made from III-V semiconductors with embedded emitters have the potential to provide revolutionary lighting concepts and devices, with new functionality that goes far beyond what is available in existing technologies. Specifically, we use Mie-resonant metasurfaces made from semiconductor heterostructures containing epitaxial quantum dots. By controlling the symmetry of the resonant modes, their overlap with the emission spectra, and other structural parameters, we can enhance the brightness by 2 orders of magnitude, as well as reduce its far-field divergence significantly.
RESUMEN
Some specific designs on the electron blocking layer (EBL) of blue InGaN LEDs are investigated numerically in order to improve the hole injection efficiency without losing the blocking capability of electrons. Simulation results show that polarization-induced downward band bending is mitigated in these redesigned EBLs and, hence, the hole injection efficiency increases markedly. The optical performance and efficiency droop are also improved, especially under the situation of high current injection.
RESUMEN
The advantages of blue InGaN light-emitting diodes (LEDs) with AlGaN barriers are studied numerically. The performance curves, energy band diagrams, electrostatic fields, and carrier concentrations are investigated. The simulation results show that the InGaNAlGaN LED has better performance than its conventional InGaNGaN counterpart owing to the increase of hole injection and the enhancement of electron confinement. The simulation results also suggest that the efficiency droop is markedly improved when the traditional GaN barriers are replaced by AlGaN barriers.